Yes, I discovered my primary Windows 7 machine with the same problem yesterday. Faffed around for the best part of an hour trying the various 'cures' on offer on the www and discovered that eventually it came good. I'm not sure which combination actually did the fix. On reflection it may well have been as simple as that described by Philoctetes above; I recall that was in the things tried ....
It had already been tardy in actually updating from the startup prompt for some months, and had to be manually sent to work from the drop down menu under the Start button.
I've yet to try the W7 laptop to see if it has the same challenge waiting for me.
Regards
FOR