1. I get the message "Windows can't update important files and services while the system is using them. Save any open files and restart the computer. and then try to check the new updates." and I am asked to reboot
2. Update history says Definition Update for Windows Defender - KB915597 (Definition 1.139.1946.0) Successful Important Date installed 14/11/2012 (today)
3. After restart: update history still indicates the above installation was successful yet there is also an indication that "most recent check for updates - never, updates were installed - never". Red x message tells me to check for updates again but then loop back to no.1 message.
4. Tried unchecking all services that were not Microsoft and restarted but problem remains.
Any way out of this loop? Thanks.