Vista - services do not start: spoolsv, VSS and others

since yesterday, a number (i would say 5) services do not start anymore, and
I am unable to restart them:

-spoolsv says: file not found
-svv tells me: file not found
The logfile is full of errors on non starting services..

Also, the settings menu has disappeared.
If I take a look in the windows system32 directory, both files exist. also
%systemroot% is defined correctly.

As the shadow server copy was working, I could have restored a previous
point, but i cannot..
I did a chkkdsk, but the disk is fine.
The system is a brand new amd with win vista home premium 64, 2Gb etc. It
has been working fine for a few weeks.
Recently I only installed Nero 7 (but the system has been working afterwards
(i think, not 100% sure). And I installed a synology NAS, the system has been
working fine after that install 100% sure.
I am running avast antivirus, and disabled it to check the effect (none).

so if someone could help me....