A lot of my users have been complaining about an issue they are experiencing since we upgraded from 5.0.21 to 6.0.5 a couple of weeks ago. When they go to compose a new message (or forward a message) the cursor (focus) should be at the "To:" field, ready for them to start typing an address or name for auto-complete. Instead what they are seeing often is that the focus is completely lost. They have to click, and sometimes even click a couple of times, in the To: field to get things back to normal. The frustrating thing about this behavior is that it doesn't happen all the time and we can't recreate the problem on-demand, so it is next to impossible to file a good bug report.
I have a hunch that this issue may be related to bug 42010 regarding copy/paste functions while in HTML compose mode and using IE. Personally I use Firefox and Text compose mode and never experience the issue. However, I did force myself to use IE and HTML mode for a while, and I did see it happen. I've tried getting people switch over to Text compose mode, especially since I feel that all the pretty formatting available in HTML compose mode is unnecessary for email. But this is really only a workaround, at best.
Anyone else experiencing this problem?