LOL - I'll go with the shorting, poor contact issue - this really made my day thanks for the hilariously funny replies ! You have some sort of fluke thing happening there is no way rubbing your PSU and touching your case would make ANY difference - you either have a contact problem or a failing PSU that revives when rested........ When I read your post it reminded me of that bottle you rub and the genie comes out of the bottle and you make 3 wishes ! Dry air humid that would have absolutely nothing to do - I have used my PC in humidity levels as low as 35% and as high as 75% RH !
Whatever you do make damn sure you don't open up that PSU and start rubbing its insides, or rub anything else for that matter, you'll end up with more trouble ! ;-)))
Check that your motherboard is properly secured to your case, no bent pins/contacts, or swap PSUs, your hands will become sore from all that rubbing ! :)
You have had various strange issues with this rig in your many adventures. Is this the same machine that had the sparks and smoke?
Wait his rig sparked and smoked? Hell it sounds very well to be a dying PSU. Anyone got the link to this, i would love to read it for helpful information and hilarity (i've done that once myself, but that was me at high school switching the input switch on the back of the psu to support 220V, wee was that a fun result)