PC ground loop?

[Executive Rob]

Hi, hope someone can help... got a pretty strange ground loop problem but not sure how to fix it.

I discovered the problem after recently trying to reamp some distorted guitars, but the signal I get through the amp is muddied up with mains hum. I've located that my computer is the cause of the problem but have no idea how to fix it.

I've been toying with the idea that there's not enough spacers separating the motherboard from the case and that maybe the motherboard is being earthed through the case rather than the PSU. But if that were the case, wouldn't my computer be completely fried?

This is a pretty major problem as I can't do any reamping for the recording I'm working on at the moment... Can anyone help?

Cheers,

Rob