800700C1 KB977165 and verclsid

Our Vista laptop has developed 3 problems recently, which are probably all related. Can anyone help?

Windows Update keeps on trying to install KB977165, sometimes successfully, but it keeps re-appearing.

Clicking on Check for Updates now fails with error 800700C1.

It also often shows an error with a DOS box title C:\Windows\system32\verclsid.exe and a message 16 bit MS-DOS Subsystem saying The NTVDM CPU has encountered an illegal instruction.

We did have some software for 2 HP printers installed. I've uninstalled one of them as this was suggested as being a problem.

Any other ideas pls?