You can do three things:
1. Wait 15 minutes
2. Set your clock forward an hour
3. The following
Do the following:
1. Open Start Menu -> Choose "Run"
2. Type "regedit" and hit enter
3. On the left, find "HKEY_CURRENT_USER" and expand it
4. On the left, find "Software" and expand it
5. On the left, look for a random 9-12 digit number, e.g. "2007839768" and expand it
6. On the left, look for a "LastUpdate" key
7. Right click the "LastUpdate" key and delete it
Then try.