[Evolution] "Error while fetching mail, file is encrypted or not in a database"

[Greg Vickers <daehenoc optusnet com au>]

Hi,

I have a user who has had a strange problem with Evolution in Ubuntu. 
It has only happened twice in the last two months:  When checking email, 
Evolution will display message in the status bar at the bottom of the 
Evolution window, "Error while Fetching Mail".  Clicking on the error 
message icon (orange triangle) gives a window with the title "Evolution 
Error" with the body information "Error while Fetching Mail", "file is 
encrypted or is not a database".

Searching for this error brought up this page: 
http://osdir.com/ml/evolution-list/2011-03/msg00001.html  I performed 
the fix described on this page and it resolved the problem.  I thought 
it was a once off and left the user to it, only for the same problem to 
happen a few weeks later.

I've collected a bit of information from this computer:
~/.evolution$ du . -csh
8.5G    .
8.5G    total

Version:
evolution 2.28.3-0ubuntu10.2

$ uname -a
Linux damien-desktop 2.6.32-30-generic #59-Ubuntu SMP Tue Mar 1 21:30:21 
UTC 2011 i686 GNU/Linux

Executing evolution from the command line:
$ evolution
(evolution:5556): camel-WARNING **: something went wrong terribly during 
db creation

folders.db list (sanitised)
$ find . -name folders.db
./mail/local/folders.db
./mail/pop/(useremail)@(domain) com mail (domain).com/folders.db
./mail/vfolder/folders.db

This user shuts their computer down each night and starts it back up the 
next day, so it's not left on for days.

So I was wondering, is this a known problem, should I log a bug, and 
what are the chances of it happening again?  I can keep going and 
removing the folders.db files and revisiting all the folders to recreate 
these db files, but that isn't much fun at all.

Any help appreciated!

Thanks,
Greg