My email store was about 4Gb, quite stable (I have run the 2011 version since its arrival). Because of recent troubles, ably resolved on this site, I had to temporarily shift many files out, and eventually back in. With lots of backup copies during this, the ending volume was about 8Gb.
Then I deleted all the unneeded files. Previously the compacting variable was untouched, at the default of every 100 program exits, no problem. Now I set it to every 1. It refused to run. So I set it to every 2. It exited normally on the "off" times, but on the "on" time it produced the error message
"The folder is currently in use by WLM or another application"
It does this even when I close everything, reboot and immediately run WLM and exit. And the message store is now up to 9Gb.
Is there any fix, short of reinstalling?