title: DateTime.Now in .NET sometimes wrong?
body: <p>In my web app, when user clicks a "START" button, I record the time by <code>DateTime.Now</code> and save this to sql server db.
  This operation is used many times in a day. And sometimes, one or two days, it record the wrong time.
  I traced all my code to ensure that there's nowhere in my code update this column value.
  Notice that, my web app is running entirely on client machine (IIS, sql server express).
  I'm thinking that maybe DateTime.Now recored the wrong time.
  Please give some suggestions?</p>