Reading from I see repairs are all over the map. Since we are not working with a full retail Vista install or DVD then you have to check your backups and use the recovery media to put the machine back to its factory condition then restore your files and apps.

Given only the story so far I can't offer any idea which of the issues that cause this so I can't pick out any specific fix. But there is no Windows Vista RETAIL DVD so we are severely limited to what repairs can be done.

In case your forgot to backup your files, here's an article about that ->