Windows 7 freezing, explorer.exe freezing when login account after

This has happened twice this week now, first sunday, and then just now, so I am becoming very concerned.

The only thing that remains consistent is that I'm playing a 3D game with audio on. Completely different programs each time. The screen would freeze up and so would the audio, and my keyboard/mouse don't respond at all. I resort to doing a hard reset with the computer power button.

Each time, when I log in again, explorer.exe is frozen. the taskbar appears, but nothing on the desktop, and after a couple seconds it all freezes up, with the busy mouse symbol when I highlight taskbar. I can still move mouse around though.

I can do ctrl+alt+delete at this point at least. Restarting explorer.exe doesn't work, so I try logging out in that menu, which does work, although slowly.

I've tried scanning for virus and also a system restore to earlier point, no difference.

The only solution so far has been to simply log in safe mode - which DOES work by the way - and create a new account from scratch.

Last time I cut/paste almost everything between old account and new, this time I will only do basics like save games and documents/music/video.

Can anyone please explain or help me understand why this is happening? I'd hate to have to keep restarting a new account, its extremely frustrating to set it up how I like all over again.

Here's my system info:

I have a Compaq CQ5210f.
**Athlon II x2 2.7 GHz processor (65w)
**M2N68-LA Narra5-GL6 motherboard
**3GB DDR2 SDRAM memory
**500GB hard drive
**250w power supply
** 1gb DDR3 Radeon HD 4650 graphic card

Thank you, I look forward to responses and ideas.

P.S.: I highly doubt the graphic card itself is to blame, despite being in a 3D program each time, unless it's something about the settings itself. I had gone to this very same forum awhile ago to check and be sure that card was ok for this machine and got affirmatives, so I bought it, and it's worked just fine.