I recently started to experience a hanging problem that happens intermittently. I didn't experience this problem before. However, on the previous install of Windows Vista, I had experienced this problem as well. The computer would almost freeze during normal use. This happened during web browsing. I was using Firefox on Vista and 7. The Task Manager showed the CPU usage at anywhere from 50-90%. Sometimes, for both OSs, the "unresponsive plugin" message would appear. I suspect, it has something to do with Firefox. However, this time(Windows 7), I am getting a message occasionally during normal web browsing. A Firefox tab fills up with a "Urgent Firefox Patch" and a download file(some script file) requests to be downloaded. Of course, I don't click on the "download" button. I just close the whole window, and it disappears. I am suspecting that my computer is infected.
Any ideas would be greatly appreciated. Malwarebytes is installed and didn't find anything. Avast Free version didn't find anything, except for PUPs. By the way, Avast presented me with a message that some plugin was giving a problem and I uninstalled it, as per Avast's recommendations. I have a screenshot, if needed.
I did start a topic about the same drive-by attack some time before, a few months back I think. I am just concerned that it happens frequently now and that it happened before as well.
I do have all the OS patches, AV is running. My OS is WIndows 7 SP1.
Thanks in advance.