We have the same problem at my wifes computer: after a reboot all services fail, no access to the drives, basically everything fails with the access error 0x80070005.
Startup Repair did not help.
Cannot access System Restore (or any other services) in Safe Mode either.
Rebooting last working configuration does not work either.
Only change we could think of was unplugging an USB drive without safely removing it first.
two hours earlier we swapped graphics adapters (from a 9600 GT 512 to a 9600 GT 1024) and used windows update to update the
drivers, but system rebooted fine after this.
rather puzzled here, any ideas?
thx in advance
EDiT: oh and btw: hi to all. been reading the forums for some time and should at this point thank you all. great community and probably the place with the most valuable advices related to Seven.