I've gone through the MRI door before and gotten the defibrillator upgrade, but for some reason it won't open anymore. I've tried loading to an earlier point and even starting a new game to no avail.

OCZ Vertex 2 SSD 180gb
Phenom II 940 @ 3.5ghz
8gb ddr 2 1066
radeon 5850 (I have a second one, but I disabled crossfire)

I swear there's just a hole in the wall that mutants come out of that you have to run through?

The door is closed and there's no hole in the wall anywhere. The first two monsters came running out as I approached the MRI room, but now nothing.