user156: I have a particular bad habit when I play chess. I play reasonably well (at least by the standards of people I play with), and am quite careful with my pieces. But in about 80% of games I play, once I get into a good position - one or two pieces ahead and in control of most of the board - I nearly always move my queen to attack something and then lose her. This is usually due to an unappreciated threat (sometimes I've even seen the threat a turn or two before).
Is this a recognised problem for many players, or is it just me? If it is recognised, are there any recommended strategies to overcome it?

user142: Are you playing fast chess? If not: before touching anything on the board, take a deep breath and double or triple check the move you are considering; maybe even force yourself to take an extra minute to review a move after you think you've decided. Try to figure out what the opponent's best move would be in response to your move. I'm sure there are many other techniques to help you not blunder, but hopefully that will get you started.
If you are playing fast chess, then yes, blunders are relatively common. 

user46: For standard time controls, this should only happen to beginners (at a frequency that is considered more than rare), and is not much different from other tactical blunders (unless you only have a problem with the queen but not other pieces, then please check with a certified psychologist). For faster time controls, practise more and improve your tactics (probably more of the latter).
To end, I might add the following quote by Teichmann:

Chess is 99% tactics.

Of course the quote isn't 100% accurate, but it is generally reflective of play between players under master strength, so don't feel bad unless you are planning to become a master. Masters may lose a queen, but not to simple tactics since they are supposed to be able to calculate longer lines and see deeper. 

user17: It seems like you are trying to "push" things, once you get ahead. So you put your queen out front and get it "snapped off."
It should be other way. Once you are ahead, let your other pieces do the fighting, and keep your queen in reserve (except to trade off the other queen). Eventually, you'll end up with a piece ahead, with the queens off the board. Then your extra piece will win.

user167: It's certainly not just you. While you describe a particular blind spot involving your queen, the more general phenomenon of throwing away sizable advantages is a very common one in chess, and it can be tough to kick. Here's a well-known saying that seems to be due to longtime U.S. champion Frank Marshall (and I'm paraphrasing):

The hardest thing in chess is to win a won game.

I've read folks like Vladimir Kramnik echo this very point as well (as have thousands of others, I'm sure). So this kind of thing is something that affects the very best out there, not just you. There can be many reasons behind this kind of difficulty (e.g. stubborn, defiant resistance from the player on the losing end), but the primary factor that the winning player can remedy himself is simply to avoid "relaxing" too soon. After all, as your experiences show, even a huge material advantage can disappear if you let your guard down even a little bit and blunder away a queen.
Something I noticed long ago in my own games is that if I allow myself during the game even just to briefly imagine a future in which I've already won (e.g. hypothetical thoughts of who I'll be playing in the next round of a tournament once I've won), then things often become much harder the rest of the way, even if I immediately catch myself after the fact and refocus on the game. Is that real, or all in my head? It doesn't matter, because if it's in my head that's enough to affect my chess play.
Refusal to consider any game won until it's actually over, coupled with constant tactical vigilance, will go a long way to avoiding the pitfall you've described. Exactly how to arrange for that in your own head will vary from person to person, of course, but that general approach is important. Basically, what I'm saying here goes hand in hand with the nice point Wes makes in his answer (slow down, take a breather before moving); take every move in the game just as seriously as any other, whether it's the first move of the game, or you're up three pieces, because the cruel truth of chess is that an entire game's worth of brilliant moves can be ruined with a single bad one.

156: <p>I have a particular bad habit when I play chess. I play reasonably well (at least by the standards of people I play with), and am quite careful with my pieces. But in about 80% of games I play, once I get into a good position - one or two pieces ahead and in control of most of the board - I nearly always move my queen to attack something and then lose her. This is usually due to an unappreciated threat (sometimes I've even seen the threat a turn or two before).</p>

<p>Is this a recognised problem for many players, or is it just me? If it is recognised, are there any recommended strategies to overcome it?</p>
 142: <p>Are you playing fast chess? If not: before touching anything on the board, take a deep breath and double or triple check the move you are considering; maybe even force yourself to take an extra minute to review a move after you think you've decided. Try to figure out what the opponent's best move would be in response to your move. I'm sure there are many other techniques to help you not blunder, but hopefully that will get you started.</p>

<p>If you are playing fast chess, then yes, blunders are relatively common. </p>
 46: <p>For standard time controls, this should only happen to beginners (at a frequency that is considered more than rare), and is not much different from other tactical blunders (unless you only have a problem with the queen but not other pieces, then please check with a certified psychologist). For faster time controls, practise more and improve your tactics (probably more of the latter).</p>

<p>To end, I might add the following quote by Teichmann:</p>

<blockquote>
  <p>Chess is 99% tactics.</p>
</blockquote>

<p>Of course the quote isn't 100% accurate, but it is generally reflective of play between players under master strength, so don't feel bad unless you are planning to become a master. Masters may lose a queen, but not to simple tactics since they are supposed to be able to calculate longer lines and see deeper. </p>
 17: <p>It seems like you are trying to "push" things, once you get ahead. So you put your queen out front and get it "snapped off."</p>

<p>It should be other way. Once you are ahead, let your other pieces do the fighting, and keep your queen in reserve (except to trade off the other queen). Eventually, you'll end up with a piece ahead, with the queens off the board. Then your extra piece will win.</p>
 167: <p>It's certainly not just you. While you describe a particular blind spot involving your queen, the more general phenomenon of throwing away sizable advantages is a very common one in chess, and it can be tough to kick. Here's a well-known saying that seems to be due to longtime U.S. champion Frank Marshall (and I'm paraphrasing):</p>

<blockquote>
  <p>The hardest thing in chess is to win a won game.</p>
</blockquote>

<p>I've read folks like Vladimir Kramnik echo this very point as well (as have thousands of others, I'm sure). So this kind of thing is something that affects the very best out there, not just you. There can be many reasons behind this kind of difficulty (e.g. stubborn, defiant resistance from the player on the losing end), but the primary factor that the winning player can remedy himself is simply to avoid "relaxing" too soon. After all, as your experiences show, even a huge material advantage can disappear if you let your guard down even a little bit and blunder away a queen.</p>

<p>Something I noticed long ago in my own games is that if I allow myself during the game even just to briefly imagine a future in which I've already won (e.g. hypothetical thoughts of who I'll be playing in the next round of a tournament <em>once I've won</em>), then things often become much harder the rest of the way, even if I immediately catch myself after the fact and refocus on the game. Is that real, or all in my head? It doesn't matter, because if it's in my head that's enough to affect my chess play.</p>

<p>Refusal to consider any game won until it's <em>actually</em> over, coupled with constant tactical vigilance, will go a long way to avoiding the pitfall you've described. Exactly how to arrange for that in your own head will vary from person to person, of course, but that general approach is important. Basically, what I'm saying here goes hand in hand with the nice point Wes makes in his answer (slow down, take a breather before moving); take <em>every</em> move in the game just as seriously as any other, whether it's the first move of the game, or you're up three pieces, because the cruel truth of chess is that an entire game's worth of brilliant moves can be ruined with a single bad one.</p>
