I got the above error when trying to generate a strong name key running filemon (see www.sysinternals.com) it showed that there was a file access error for me on the folder:
C:Documents and SettingsAll UsersApplication DataMicrosoftCrypto
I had to give myself permissions on this folder and tell windows to propogate them to all the child objects then I could successfully generate a key using
SN.exe -k mykey.snk
This is the first time I’ve used filemon but I doubt it will be the last.