Just note I have the same issue - have had it ever since went to Win 7 64 bit about last Summer.
Have seen the various notes here with many having the same problem.
Have tried to run as admin which solved for someone but not me.
Easy test is change a name on a desktop short cut and with fences on explorer stops and has to restart. Disable Fences and no longer a problem. Enable again and the problem returns.
It has to be Win 7 64 bit vs Fences related as there are many reports of it on many types of hardware, different anti virus etc. I have fast i7 chip 2 fast dual video cards (run 5 monitors) 4 gigs of RAM etc but I don't think its hardware related.
I also get the Explorer crash at other odd times can't id a specific reason. But when disable Fences goes away. I like fences but not the wasted time with all the Explorer crashes. Have latest version of fences.