and be careful.

I had a pc in for repair a few years back that worked lying flat but not standing up.
So I stood itup, went off, laid it flat started up. Did this a few times for novelty and then it blew up !
Huge spark, big bang, lots of smoke - I nearly wet myself.

Bloody psu had a loose capacitor - one of the big ones. It had been rocking on it's contact and eventually decided it had had enough and just exploded.

So just be careful :-)
Hopefully it's just a loose wire.