Computer Freezes Occasionally

My computer freezes occasionally, and I have no idea why. It never used to happen on XP, which means that I suspect that is with Windows 7 somewhere. However, I have not found anything in an internet search.

The computer freezes most often when it is playing a video or streaming music, which makes me suspect that it is a problem with the graphics or sound card. Unfortunately, Windows doesn't create a log of the problem, so it leaves me drawing blanks.

I had the RC version of Windows 7 and encountered no problem with it before, yet it just happens. I have added to extra sticks of 1gb DDR2 RAM along my current 2x512 DDR2 RAM. The problem did happen before then. I have also ran the memory test which also found no problems with it.

The hardware of my computer is outdated by somewhat 5yrs, yet other than the occasional crash, runs perfect. I have the latest drivers installed for Windows 7.

It could also be due to the heat, but I am not sure how high the temperatures of my hardware can operate at before it becomes unstable. I have seen teh graphics card around 65c, but its base temp is usually 53c. On the otherhand there isn't really much circulation of air around the back of the computer.

SiSoft Sandra does come up with a message under peformance tips:

quote sisoft sandra

Memory bus speed exceeds chipset rated memory bus speed. If you’re over clocking the system just be aware that it may not be as stable as you may think. Also you may be over clocking the memory modules themselves.

How would I sort that out so? I am not overclocking the system, or atleast, I'm not aware that I am. How can I make it operate at the chipset rated speed, and will it reduce the performance of my computer by much?

I don't know if it would mean anything but I've listed the main computer hardware below.

The 512MB RAM is manufactured by Swissbit, the 1GB RAM is manufactured by Crucial.

-----Hardware-----

PSU:
Motherboard: MSI MS-7204
Processor: Intel Pentium D CPU 3.00GHz (Dual-Core)
Installed RAM:
Slot 1: 512MB DIMM DDR2 4-4-4-12 8-16-4-2 1T
Slot 2: 1GB DIMM DDR2 5-5-5-16 3-20-5-3 1T
Slot 3: 512MB DIMM DDR2 4-4-4-12 8-16-4-2 1T
Slot 4: 1GB DIMM DDR2 5-5-5-16 3-20-5-3 1T
Graphics Card: NVIDIA GeForce 6700 XL 128MB DDR3
Audio: MSI/Intel 82801G (ICH7) High Definition Audio

I'm running 32-bit Windows 7 Ultimate, btw.

have you tried safe mode temporarily? also, have you tried booting on the absolute minimum? one stick of RAM, no video card if you have onboard display, only your main hard drive, no optical disk drive, no other pci cards.

while youre at it, i need details about the make and model of your psu, as well as its maximum wattage and combines +12 volt amperage ratings.

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I have tried Safemode and it works fine. When you mean boot to the absolute mininum, do you mean going into config and unchecking everything that autostarts?

if safe mode is working fine, then it rules out some hardware. as for booting at minimum, i was talking about hardware. as in pulling out hardware that is not required for running the computer.

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I'd try just one stick of RAM but that would leave me with 512mb of RAM and would probably lag everything out completely.

that doesnt matter. youre not aiming to use it like this for long.

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Just seeing Speccy, and it shows that from startup, my graphics card peaks at 65°c after a few minutes. I don't really have good circulation in the computer, and I don't really know if 65°c is hot or not. I have took off the side panel in an attempt to increase air ventilation.

65 degrees is fine. video cards can take up to about 100 degrees before frying. some even more, but its best if it doesnt go over 90 degrees. however, that reading is not taken while the card has undergone a minimum of 5 minutes of 100% load, correct? because that is what will matter.