user26717: I have been working merrily along with CH340 to make Com10 work.  It has been working flawlessly but now I am getting various messages like it can't open the port then the programmer is not responding.  It tries several times before giving up.
This was working fine yesterday.
I tried uploading to a raw board not connecting to anything and am getting the same result.
Suggestions?

user27157: This problem occurs quite often with all the boards. Here is how to troubleshoot it.
1 - Unplug the Arduino.
2 - Upload the program WITHOUT any boards connected to your computer.
3 - Replug your Arduino.
4 - Upload the program WITH your Arduino connected to your PC.
If this doesn't work, read this post by Nick Gammon.

user26717: OK, problem solved.  I wish I knew enough to be able to say why it worked, but here is what did the trick:
I uninstalled the IDE.
THEN REBOOTED.
Then installed the IDE (version 1.6.10) again, this time not selecting the USB driver.
THEN REBOOTED.  
In Device manager it still shows the CH340 driver on COM14
All my sketches and the two libraries (DHT and LCD) in the documents/Arduino directory were unaffected.  
And now it will upload to my boards just fine.  
This is one of those times where I can't explain why, but I can tell you for sure that it worked for me.  I had tried uninstalling/reinstalling, but without the rebooting in between.  Perhaps that was the crucial step that needed to be taken.

26717: <p>I have been working merrily along with CH340 to make Com10 work.  It has been working flawlessly but now I am getting various messages like it can't open the port then the programmer is not responding.  It tries several times before giving up.</p>

<p>This was working fine yesterday.</p>

<p>I tried uploading to a raw board not connecting to anything and am getting the same result.</p>

<p>Suggestions?</p>
 27157: <p>This problem occurs quite often with all the boards. Here is how to troubleshoot it.</p>

<p>1 - Unplug the Arduino.</p>

<p>2 - Upload the program <strong>WITHOUT</strong> any boards connected to your computer.</p>

<p>3 - Replug your Arduino.</p>

<p>4 - Upload the program <strong>WITH</strong> your Arduino connected to your PC.</p>

<p><a href="https://arduino.stackexchange.com/questions/13292/have-i-bricked-my-arduino-uno-problems-with-uploading-to-board">If this doesn't work, read this post by Nick Gammon.</a></p>
 26717: <p>OK, problem solved.  I wish I knew enough to be able to say why it worked, but here is what did the trick:</p>

<p>I uninstalled the IDE.<br>
THEN REBOOTED.<br>
Then installed the IDE (version 1.6.10) again, this time not selecting the USB driver.<br>
THEN REBOOTED.  </p>

<p>In Device manager it still shows the CH340 driver on COM14</p>

<p>All my sketches and the two libraries (DHT and LCD) in the documents/Arduino directory were unaffected.  </p>

<p>And now it will upload to my boards just fine.  </p>

<p>This is one of those times where I can't explain why, but I can tell you for sure that it worked for me.  I had tried uninstalling/reinstalling, but without the rebooting in between.  Perhaps that was the crucial step that needed to be taken.</p>
