Just adding to this issue, I've always experienced this same kind of hanging effect with Firefox 3 (never FF2) on my system (Vista 64 bit fully updated). The only difference is for me it isn't as significant like hanging for 1 minute which I'm thinking may be because of my computer's hardware performance, but there is definitely something going on. This has happened ever since I've had FF3 (which was since it came out) and every version that has come out since hasn't done anything to the problems (versions 3.0.0-3.0.3 all have done nothing to this including all previous avast! updates).
Other details I've noticed is that there's a slow kind of response when FF3 closes--the window closing looks like it lags (this is using Vista's Aero theme) and even once it's gone the FF3 process will still be in the task manager running for a short while before finally shutting down (which isn't normal from past experience with firefox). I sometimes get errors too where Firefox says something about it being already running or that it's busy shutting down (I forget--it's been a while). Using the built-in function to clear cache in FF3 lags significantly too than before on FF2, which used to be an issue before with avast spewing out tons of error messages just because of me deleting temp files. Then again I'm getting similar errors again (refer to the link at the end of this post).
Oddly enough the reason why I never posted here was because I honestly never thought avast was linked to it, but after reading these posts, it definitely seems relevant. It's been around for quite a while now and looks like it affects Vista users the most as I (so far) haven't seen any drastic issues with FF3 closing on my family computers that run on XP SP3 with avast. I could be wrong though.
The only other "issue" with avast I've been able to identify so far (mentioned it earlier) is that the old error messages for deleting temp files seems to be back. It isn't critical but it is something that has been lingering around for quite a while now. My old post on this is located
here for those that are interested. Not sure if this is relevant at all but I figured it should be added to the list here as well while we're at it.
Edit: Did a short test with avast's shields down while continuously running and closing firefox in different scenarios. I can confirm that there's a difference in responsiveness and speed with the shields down.
