Flash 10.0 to 10.1 Issues?

We are having some problems with textfields that worked fine with Flash Player 10.0 upon upgrade to 10.1.  The biggest problem is that frequently we have no errors such as pauses/delays in the interface and so forth.  What has changed from 10.0 -> 10.1?  What should we watch out for and really look for in terms of changes and thus what may need to be fixed or done properly?

There is one error that has cropped up for us that was mentioned elsewhere in the forum here:

ArgumentError: Error #2008: Parameter validity must be one of the accepted values.

    at flash.text.engine::TextLine/set validity()

at http://forums.adobe.com/thread/612819

I certainly wish we had more to post from the debugger, but there is nothing very helpful in terms of output except that previous note.  If I run into more, I certainly will share them, however this is a very unproductive and problematic issue.