Help! PC freezes at "windows is starting up" screen, what's wrong?

[coco]

Operating system: Windows XP Media Center
AMD Athlon 64 X2 Dual Processor

I spent all night working on my computer (yeah, I didn't sleep). In the morning, while I was editing some graphics in Photoshop CS3, my PC froze but I wasn't able to close the program nor restart so I just shut down the computer by pressing the power button. When it restarted I was unable to get past the "windows is starting up" screen. It freezes right there. Even the mouse pointer freezes.

Does anybody have any idea of what may be wrong? I have a lot of work to complete and I'm hoping it's not a software issue because I don't want to lose my data. Please help me guys.

[coco]

Any software that can help me solve this problem??

[Train]

When was the last time the dust and junk was cleaned out of the case?

A overheating video card will flat lock things up and you were using heavy like.
May need to remove the card and make sure it is clean.

[Midknyte]

Since you have the case open to check for dust, check for bad caps. You might also want to reseat your ram. It's not a definite, but at least you start eliminating the suspects.

You may also want to run a memtest and hd diag.

[Ol'Tunzafun]

What was it that you were working on through the night?