... but what problems has the System Restore caused that you don't know about yet? I would not use that to solve problems. I would only use it if someone's computer won't boot, I can't solve it by normal means and then I'll probably be doing a clean install afterward if anything at all doesn't feel right. It can make it easier to back up someone's files if the system will at least boot up.

System Restore is NOT a disk image. It does NOT restore your computer back to a previous state. It only reverses changes that it has tracked, sort of like incremental deltas. Changes that occur through legitimate means, like software installs get tracked. Changes that occur through illegitimate means like malware doing low level things, or old software installers, or anything done in Safe Mode will not be tracked. Sometimes legitimate changes don't get completely tracked and restored and it can leave your system in an inconsistent state with incorrect file versions. Many restore points also FAIL and say "no changes were made to your computer" yet they HAVE. I've seen it with my own eyes. I completely distrust it.

It also restores the registry, which in your case was what solved the problem. You could have found and deleted the policies using the registry editor, or you could have just restored a copy of the registry using the system restore data. (e.g. on UBCD4Win there's a utility that does that)

You got lucky this time... there weren't many changes to your system and your problem was just registry related.