Hi razzle,
I don't use IE so can't tell you from personal experience, but I have read of other people having buggy issues with the IE7. I don't think you're alone in going back to IE6. I think there's another post here about some bug fixes, but maybe that was a different forum.

Edited to add: found it. mrsd posted on a couple of threads here about some issues with IE7
One of them is

Fix for .DLL errors and IE 7.0...
http://neurotalk.psychcentral.com/showthread.php?t=8484