Fresh start. Reformat. OS Reinstall.
Whatever you call it, no matter how technology savvy you are, there's a time to backup your files and erase the hard drive.
When would you need to take such extreme measures?
If you can't get hibernate or standby to work anymore. If the networking protocol is broken and you can't get online. Or if you've had a horrible malware or rootkit breakout. Sure, you can TRY to reclaim control of your PC and have a battle with the beast, but can you really trust your OS anymore? A Fresh start is the only way to bring your computer back to life and ensure a fully optimized system. It can also save countless hours of troubleshooting and tweaking a misbehaving machine.