If you look at Firefox Add-ons under Tools, it indicates that particular plug-in is not compatible with Firefox 3.5.2.

I was having a problem with my status bar freezing or hanging when I tried to get in some of the sites I visit. Also our cable company has been doing maintenance in our area so I called them. The tech I talked to the second time said it sounds more like a router problem. I told him I have Linksys, he replied so did he and he sometimes had to unplug and plug it back in, 2 or 3 times a day to work on line. He suggested I disconnect the router for a few days to see if my PC works properly. I did that early this AM and it has been fine so far. I will know more in the morning when I turn the PC on. Since some others had a problem with freezing/hanging on the status bar, this info might help them.

Looks like it's not really being supported. In Firefox, if you look at Tools > Add-on's > Ad-block Plus > Options > and then Filters > Add Filters Subscription, there's some info that refers to what I mean. But we'll have to wait and see if someone starts paying attention to it again, I suppose.

try running your firefox in safe mode to do that go to start all programs mozilla firefox and select run firefox in safe mode see if the problem occurs then, if so it is likely one of your add-ons that is causing the problem.