I was so pleased upon upgrading to Firefox 4 to no longer have Windows Live Messenger crashing the browser every time I opened Hotmail and had an active conversation window. I don’t know if it was Microsoft or Firefox at fault but the problem seems to have gone away now.
I’m less pleased, sin embargo, that two of my plug-ins for the previous version aren’t yet supported. Then again, one of those is old and seldom used and the other (IE Tab) should follow in time.
Problem solved!
IE Tab 2 is an improvement on the original IE Tab and is FF4 compatible already.