Beep code and random freezing

I've noticed my computer freezing a lot lately for no apparent reason. Its happened in Firefox when autoscolling with the mousewheel and when viewing full screen video. Running Prime 95 causes the machine to instantly freeze as soon as the test starts up. Memtest and the Windows memory test came back with everything fine. I reset and updated the bios with no luck.

I cannot start up the machine without having to press the reset button but starts up fine after I press it.
When booting up I get 4 beeps then the computer starts up. I don't know how to interpret these beeps so here they are.
http://www.supload.com/listen?s=3QzTQC

Any suggestions would be appreciated.

My bad, duh.

AMD Phenom II X4 945
MSI 790GX-g65
Crucial 4gb 1333
HIS Radeon HD 4890
WD Cavier black 750gb
OCZ Steathxstream 700watt
Vista Home Premium 64bit

I think you have a short ciruit issue, there might be a contact between your case and your motherboard. Screws that hold the motherboard might be too tight. Also check that you have connected the Case's wires properly to the motherboard's jumpers (power button, reset, lets, speakers etc).

Best thing to do, is take the board out of the case, and set it up out side it.

Carefully remove all parts from motherboard, leaving only the cpu, the fan. Then unplug all cables connected to the motherboard. Very carefully unscrew motherboard and take it out from the case. Place it on top of a wooden or plastic board. Try installing the components -One-at the time until you find out which is the conflicting one.

(Before you start to touch any electronic boards, dont forget to touch the metal case to remove any static that have build up in your body)

Is boop a long beep and beep a short one? What does your manual say about beep codes? Your description seems to indicate a video issue, but it could be caused by memory errors, etc. If the motherboard is under warranty, contact MSI.

It sounds like a motherboard issue, but MSI should be able to determine what the beep codes mean.

That motherboard might be different, but should have a single beep at startup indicating successful POST. Do you get a single beep when using only one memory module?

Same beeps with either stick.

Make sure that the contacts on the memory and the socket are clean.

Try removing one bank of memory modules at a time.

Try using memory modules from the same manufacturer with the same part number and speed.

Check for a faulty memory module by trying the memory in a known good system.

Trying known good memory in the system.

Check the power supply and check for power fluctuations.

If the steps above do not resolve the problem, the desktop board may be defective. Try a different desktop board.