... Huh...
Wait... What?
How'd you come up with this workaround in the first place?
I'm not sure anyone here and tell you whats wrong, or why rubbing the PSU with one hand while keeping the other on the case seems to get it running again. Perhaps your computers a little sexually deprived?
See if you can borrow a friends PSU to see if that's the issue, other than that... I'm kinda, well, speechless.