Before reinstalling Windows, try going into safe mode and using
msconfig:
1) Start -> Run, type msconfig and hit OK
2) On the startup tab, uncheck everything except LoadPowerProfile, SystemTray and ScanRegistry if they exist
3) Hit OK and reboot Windows normally
If you still have problems, go back to safe mode and try to disable your NIC (Network Interface Card) in Device Manager if you are connected to a LAN.
Don't forget to scan for viruses (which you can do in safe mode). There's also some information here on how to restore your registry to a last known successful attempt:
If all that fails, then perhaps it is time to reinstall Windows to replace any corrupted files. However, you must realize that if a device in your system is using the wrong driver, Windows won't necessarily discover the problem on its own.
~cdogg
[tab]"
All paid jobs absorb and degrade the mind"
[tab][tab]- Aristotle