I'm having the same problem, which started around the same time. It seems to be most prevalent when I try to copy something (it doesn't seem to matter whether this is via ctrl-c, or the 'copy' icon). It seems to affect Word & Excel regularly, Access occassionally and today is has started affecting Internet Explorer as well!
BTW: If it is the update from 11th, would a system restore back to before that date resolve the issue?