Windows 7 – Why Hibernate Doesn’t Work Anymore

I am having a problem with Hibernating my Windows 7 PC. When ever I try to hibernate, the screen goes blank for a while, there's disk activity and then I am presented with the Login Screen.

I've tried enabling/disabling hibernation, not helped.
When I run shutdown /h I get a error: "The system cannot find the file specified.(2)"

I've checked and "hiberfil.sys" does exist.

How can I get hibernation working again?

EDIT: Just ran shutdown /h and monitored it with Process Monitor (something I should have done at the beginning) and the only file it cannot find is "C:\Windows\rescache\rc0008":

08:10:24.6198561 AM shutdown.exe    3684    CreateFile  C:\Windows\rescache\rc0008  NAME NOT FOUND  Desired Access: Read Attributes, Disposition: Open, Options: Open Reparse Point, Attributes: n/a, ShareMode: Read, Write, Delete, AllocationSize: n/a

I went to "C:\Windows\rescache" and saw:

rc0006 (Folder)

rc0007 (Folder)

ResCache.mni (File)

Now I tried just copying rc0007 and rename it to rc0008 but I get a access denied error (even when running as Administrator). Should I bother going into safe mode and copying and renaming rc0007 to rc0008. Will it help? Does this shed some light on the problem?