i cant email you at the moment but ill try to help you from here. Ive run into this problem before.

Three main reasons is what ive locked it down to, hopefully one of them helps

1. the web browser

2. Boot drive(not sure what the exact issue is or was but a bad drive might cause the issue, even one that a test would say is fine, remember changing this requires some time)

3. Bad motherboard capacitors: seems odd but this issue is common in older motherboards, caps age and sometimes bulge or explode, this can cause random issues depending on the roll of that cap. 

Sadly this problem will likely cost you some money. id say rma that board if possible.

I recommend that you post this on the public board because nobody really looks over here.

Try running your pc in safe mode and  try downloading files

Clean your PC with a soft brush and blower,Dust off the entire cabinet, Remove all parts motherboard and GPU and clean them too. Beware of ESD take precautions ! Reset your bios.

Clean clean clean everything fans, dust filters everything !!! take your time try rubbing all the connector parts like ram,gpu, and sata ports and ssd with 99% rubbing alcohol or try using an eraser but be cautious and try not to break anything.

Check your power supply and clean it too. check if psu fans are working. Reconnect everything and install a clean os probably win 7 64bit ultimate then download all the drivers from mobo support site and install them beginning with chip-set and graphics and LAN.

Try replacing sata cables or try swapping out rams.  Borrow a pair from friend and try your luck

Hope this solves. Fingers crossed all the best.

Please respond if this solves !!

I have had this issue in the past and the culprit was a faulty ram stick. Im not saying this is true for you but you may want to switch around your ram methodically and trying one stick at a time and then test. I hope your problem gets solved.