I have just this min experienced a server side malware redirect attack on imageshack (win anti-virus 2010). I've reported the matter to imageshack, but think a warning is needed while they resolve the issue. It is a completely random redirect, done by a fake php process server side. So it seems their server has been compromised. It's the same issue experienced last year on PFO, so please don't think it is fake or bad info, if you don't get this problem when using imageshack. The fake process is completely random, and may only redirect 1 in every 1000 page views. If you get redirected, this is what you will see
What ever you do, do not click on close, OK, or hit the red cross to close the warning windows. Just start task manager (press Ctrl, Alt and delete key at the same time), and end all iexplore.exe in the processes list.