This isn't exactly helpful, but two of our work PCs had a memory issue similar to yours. For some reason all of the RAM was instantly used up - which is a fucker as you then can't work out what's wrong or do any of the obvious starting points.
Ultimately we couldn't find a solution and ended up replacing one and using a live OS on the other. Our best guess was some sort of virus, so if you can I'd try and reinstall W7?
This isn't exactly helpful, but two of our work PCs had a memory issue similar to yours. For some reason all of the RAM was instantly used up - which is a fucker as you then can't work out what's wrong or do any of the obvious starting points.
Ultimately we couldn't find a solution and ended up replacing one and using a live OS on the other. Our best guess was some sort of virus, so if you can I'd try and reinstall W7?