"The PFN_LIST_CORRUPT bug check has a value of 0x0000004E. This indicates that the page frame number (PFN) list is corrupt."
"This error is typically caused by drivers passing bad memory descriptor lists. For example, a driver might have called MmUnlockPages twice with the same list.
If a kernel debugger is available, examine the stack trace."
Set your system to capture a kernel memory dump. Bug dclive, he debugs as a hobby. With some arm twisting you could probably get Siannath or myself to look at it.
You should also start by double checking that all your drivers are up to date.