onoes my computer won't boot

This morning while I was sleeping my wife decided to make my study even smaller by moving a bookcase in. To do this she moved my computer. Now it hangs during boot when it gets to the "checking ram" stage.

I've tried swapping all the DIMMs around, nothing. Halp :(

Okay, blow out the system with a can of air, ya never know.  And how old is your ps? I had a system that used to hang at that step, ps was old, not to mention the wires were messed up from years of twisting around drives causing all sorts of shorts.