Windows XP Hangs on Restart/Reboot

[sinisterinc]

Hi,
I have a Intel 7300 Core 2 Duo 2.66GHZ with a Gigabyte Mobo and 2 gb ram, With a modded version of XP, called DarkLite installed. I have been experiencing a few problems recently, I don't think that all of them are inter-linked but I'll mention them anyway, AVG couldn't update, and still can't, i have manually updated it and scanned as well, no malware found. Now the real issue, my computer hangs on the Windows is Shutting Down screen after about 10 secs, after I command a restart. I thought this was a software issue and tried a trojan remover as it was mentioned in some of the forums. I also disabled everything at start-up with msconfig, earlier I had tried manually closing all the processes before I tried shut down. I remember this started when I noticed that the restart button on the cabinet wouldn't do anything, I opened it up and re-connected the jumpers, after which the button responds, but this problem showed up. I am quite certain that it is not a software problem, as when i go into the BIOS setup, and exit, the screen just goes blank/black and basically hangs, I have to then use the button on the cabi to restart it. The shut down is working perfectly. I was going to reset the CMOS but wanted a second opinion before. What do u say guys... what is it ?

[The Sorcerer]

The basic question:
You system configuration including the power supply.

[sinisterinc]

As i'd mentioned above : I have a Intel 7300 Core 2 Duo 2.66GHZ with a Gigabyte Mobo and 2 gb ram, With a modded version of XP, called DarkLite installed, and I have an oldish powersupply, L & C 400. 160 GB Hdd. A Samsung CD RW, yea that basically sums it up.

Another thing noticed just now, i restarted my comp, using the cmd prompt, typing shutdown -r , and guess what it worked!! I haven't tried the normal restart yet, but will do that and post if any change. Thanks for the reply!