Studio rig gone ape!

Not the best of days :-) Was making great progress on my next track and the studio PC began to give issues in the form of intermittent reboots.

This rig was built from the ground up (by me) so I know that the problem lay with 64-bit XP drivers (Sound card). So why not just re-install them?

I did - and that's where the horror story comes into play. Sound is completely different to what it used to by - almost tiny. I've re-checked all studio wiring, and even tried 3 historical drivers.

Truly at a loss for words. Almost as if I've lost the LFE portion of a setup running in 5.1 (I'm obviously powered two studio monitor speakers in stereo).

After battling for hours - still no joy. Even the VST's I've used for years sound different - like their rendering to a different clock speed.

Strange stuff. Anyone else ever had an experience like this?