|Are you certain there is no 'repair' option when you get to the safe mode menu? It needs to be the full menu, not just the basic 3 'safe mode' options. If there's definitely no 'repair' option then the first one to try is 'last known good configuration'.|
If that doesn't work then you need to look at recovering the registry entries from the 'repair' folder, either through the built-in 'safe mode command prompt or by using a Vista recovery disk.
Post back with the results above by which time I'll have found the link for the recovery procedure.
"I've always been mad, I know I've been mad, like the most of us..." Pink Floyd