Hiro - though I am not sure if this is the cause of your problem, similar issues just appeared with a recent Microsoft security update. We're having the same problem at our company.
See these forum threads:
http://www.automatedqa.com/forums/forum/post/?mode=singleThread&thread=6f0a81f8-435f-4ce2-8c00-d12a3cf9511bhttp://www.automatedqa.com/forums/forum/post/?mode=singleThread&thread=c5a7af4f-e3bd-472b-8740-4576b8c24d25Rolling back to a previous System Restore point may be a temporary solution.
Good luck.