I don't think it's the virus or hardware problems. Why don't try to reinstall your IE browser, or you can use some tools(like Wondershare registry optimizer) to fix this problems. After all, there are many browsers in the world, why not try some others. I like the Firefox very much.
Had the same issue with explorer crashing. Starting it as a new process in task manager didn't work either. As some people stated before, I seem to have fixed my problem with chksk /r Problem started after waking up from s3 sleep. It's not a hardware error on the disk, just some bad clusters, caused by win7 itself. I do have a feeling that vista sp1 is more stable.
Since some time I haven't occured any problems with explorer.exe crash. I was only doing Windows updates and KIS 2010 updates, thats all. I suppose one of KIS updates fixed the problem, or Windows. One is sure, that I didn't have any problems with this crash since about a month.