Does Firefox 4 work on a Mac?

I bought a MacBook Pro 13" a few days ago and installed Firefox 4.0.1 for OS X. It seemed to work fine for the first couple of days, but today I've had some problems. For instance, it won't load the Google Reader page properly, or YouTube.

I was a bit puzzled because I didn't have this problem initially. The pages load fine on the MacBook in Safari, incidentally. I came here to see whether anybody else had reported any issues and I've seen a thread which seems to suggest that Firefox 4 doesn't work on Macs. I'm not sure what to make of that, though, because on the Firefox download page it does say it's for OS X.

Can anybody tell me whether this version should be working okay on my Mac? If so, can anybody make any suggestions re: what might be wrong?

Thanks for any help.

Thanks, WiBu! I've just disabled all my plugins, and when I re-started Firefox Google Reader loaded. I'll go through them one by one and try to narrow it down.

Thanks again

Edited to add: I've now re-enabled them all, one at a time, closing Firefox down in between each change, and the pages that wouldn't load earlier are now loading. Does anybody have any idea why this might be?