"Disk defragmenter could not initialize" :(

I am getting the above error whenever I try to analyse or defrag my drives,

MS knowledgebase says it can happen on NTFS-formatted drives, but it happens
on ALL my drives - some of which are FAT32.
http://support.microsoft.com/default...b;en-us;274106
This started a few weeks ago, so it's not because the drives are excessively
fragmented.

I downloaded and installed Diskeeper, but get the message "Diskeeper could
not initialize" instead....

Any ideas what else might be causing this?