Computer restart issue for Tews/anyone that will help

Tews, I have read a great deal on the board before joining and have noticed how helpful and knowledgable you are. I was hoping that you wouldn't mind helping me.

I am having problems with my computer restarting, right away, every time I try to shut it down. This occurs with shut down from the Start menu, as well as the computer case. The only way to turn the computer off is to hold down the power switch on the computer case until it turns off.
My operating system is Windows 7 Ultimate 64-bit - my Windows version is build 7600 6.1.7600. My computer is an EVGA X58 3X SLI Classified motherboard with the Intel i7-975 Extreme Edition processor, the video card is an EVGA NVIDIA GeForce 295 GTX and there is an integrated sound card. It is powered by a 1KW Silverstone. My BIOS is Phoenix Technologies LTD 6.00 PG 11/25/2009 SMBIOS version 2.5.
My attempts at isolating the problem have included adjustments in the power management scheme all the way to trying to isolate the situation from booting in safe mode. Interestingly enough when I went to 'msconfig' and turned off all 'services', the computer would shut down. So, I tried adding in a few services a time until I found the guilty party. But, there was NO guilty party! I was able to add in all of the 'services' and the computer would shut down - ONCE! After that one time, I was back in the same boat.
I have also tried turning off the firewall, dis-abling the IEEE 1394, turning off the media player sharing, not allowing restart after system failure. None of these has made any difference. Of course, I have already looked to make certain that the shut down button means SHUT DOWN. I have turned off Windows update. On power settings, I have disabled the 'allow wake timers' under the sleep tab and I disabled the USB selective suspend setting.
I have even re-installed the operating system - this has not changed anything. Fortunately, I am able to enter sleep mode without difficulty. This computer is one week old and has behaved this way since I unpacked it from the box. If you have any further suggestions, they would be greatly appreciated.

Hey Myzr7, you're not Tews.

Thank you for responding. The scan had 'no integrity violations'.

There were no programs pre-installed. The anti-virus is microsoft essentials, which I have tried with it off and then on again, without any change.

First, I tried it with unchecking everything from the startup tab. Rebooted, then tried to shut down. The computer restarted right away instead of shutting down, as it had been doing. So, I assumed the culprit was not in the startup area. Next, I unchecked ALL the items from services, leaving the 'hide all microsoft services' unchecked. Rebooted, then shut down the computer - and, it stayed off. So, I added back in a few services at a time. Each time, rebooting and shutting down successfully. I was able to add back in all of the services, reboot, and then successfully shut the computer down. However, in the end, it only shut down that one time. When I tried to shut it down for the second time, after all the services had been added back, it restarted right away instead of shutting down.

I did as you suggested and hid all MS services, that left me with only three items to sort out. I unchecked all three, rebooted, and then was able to shut down - TWICE. I added each one back in, rebooting with each and shutting down TWICE with each. Ultimately, they are all three added back in and I have been able to shut down twice after they were all active. What could possibly explain this? The three items are: Adobe Active File Monitor V8, FLEXnet licensing service and NVIDIA Display Driver Service. I will say that once the NVIDIA was added back in, the windows loading screen flashed somewhat with each of the restarts. Is it possible that the NVIDIA is what is really causing me the trouble, and for some reason it is behaving now, except for the flashing? What would happen if I turned the NVIDIA Display Driver Service off on 'msconfig' and left it off? Thank you very much for helping me, I don't know a great deal about computers and this has been very frustrating for me. I have always tried to read as much as I can to solve my own problems, but this one is beginning to get the best of me. Once again, all the help has been much appreciated.