There could be so many causes for this:
1. Malware
2. Hard drive going bad
3. Faulty memory
4. Windows file corruption
If it shuts down properly from SAFE MODE, then it's likely something running in regular mode that's causing the problem. Do that test.
I'd bet on 1 or 4 though. Given that:
0. Make sure you don't have two anti-virus products running
1. CCleaner: remove all temp files found
2. CCleaner: clean registry until no more errors. Save REG file each time before fixing. Reboot
3. Run TDSSKiller (reboot as required/prompted)
4. Install and update MBAM and run a FULL scan (reboot as required/prompted)
5. If items are found, run a full scan using your anti-virus product that is UP TO DATE.
6. Run a CHKDSK and schedule for next reboot, then reboot and let it run.
7. You can run an SFC /SCANNOW to make sure windows files are okay. Reboot.
Verify shutdown after each instance of "reboot" above. Report back if no joy. Then we have to start looking at hard drive, memory and items that start when windows start. You can do the hard drive diagnostic and memory diagnostic first if you want. If you don't know how, then do the items I have listed first.