UAC: Vista Mainataince Programs-> unidentified program wants acces

Since today I have some strange problems with Vista (64bit). The System
crashed and I needed to restart. On Bootup vista got struck and told
something about a corrupt registry and that I should use the DVD and try to
restore. So did I... The first restore round repaired some file system
problems. This didn't help so I gave the restore software another try. It
offered to use the last restore point for restoring the system. This time
things worked and Vista booted as usual. But after a while I noticed that the
UAC is always complaining about Unidentified Publisher for most (all?)
maintaince tasks: Using Advanced System settings causes the orange alert for
SystemPropertiesAdvanced.exe or using the Management Console also causes the
message for mmc.exe or the command promt (cmd.exe).
I tried the Resource Checker "sfc.exe /SCANNOW" if it can tell whats going
wrong, but does not find problems. I also tested it on selected files:

$ C:\Windows\system32>sfc /VERIFYFILE=c:\windows\system32\mmc.exe

Windows Resource Protection did not find any integrity violations.

So I don't see the point why the UAC tells me something about Unidentified
Publisher. I have no idea what is going wrong and how to repair it.

After a while of messing around with checking certificates and things like
that i gave system restore another try and found a suitable restore point
some days ago. that did the trick, but I'm still quite unsure what caused
this strange behaviour.