I bought a copy of onenote. It started up ok for a month or so. Now
suddenly, it doesn't start. I get the following error:

OneNote is unable to start. This may be caused by insufficient hard drive
space or by insufficient write permissions for onenote's notebook cache files
in your user settings folder. Try to delete any unnecessary files from your
computer and then try starting onenote again.

Error code:0xE0000041

I have many gigs free on my hardrive. I reinstalled onenote. Same error.
Then, I did a system restore to a date when it was working, but vista would
not do a system restore (it errored as it tends to do about 25% of the time).

How can i resolve this error?