Okay Try this,

Click on Start -> Run or windows key+R, Then type msconfig and click on the BOOT.INI tab. Then try clicking on the check boot paths and the other install may show up.


Or you...

Yes I think that will work.

But if doesn't work you may have to reinstall the OS, if it comes to this then you can back up your data using a linux live cd.

Or If you have a large hard drive...

Have you tried allowing automatic updates?

Have you checked out that error code link?

But something must be wrong with the time settings. Look at that security certificate; Will not be valid...