alternative solution... buy a mac
sorry had to toss that out there.
its probably some app that is preventing system files from loading and telling the computer it needs to restart. Norton anti virus did this on my old Sony, so i feel your pain. When you log in thru safe mode, if you have the option to restore to a previously working mode OR if you can get windows to boot, you can do a system restore.
if there are files that you just saved between your last system restore (assuming you dont have this done automatically), then you can take out the hdd, put it in a 2.5 external hdd enclosure you can buy from bestbuy for about $60 bucks, then transfer those files onto another pc.