Got a weird one for you guys.

Go to switch my speakers for my headphones (unplug them from the soundcard)
which results in the screen completely locking and forcing me to hard reboot.

Ever heard of this? I had it fixed for a while, but i had to address another issue i was having and that somehow brought this all back.

p.s. there is no "I/O shield" installed between the mobo and the case, besides keeping dust out, don't see the need for it.

spex-

xp pro sp2

msi 865 neo2 platinum edition

audigy 2 zs

 

Maybe a dry solder joint on the motherboard when it's disturbed by things being plugged in. I'm sure there are plenty of other possibilities but that's just one that springs to mind.