All I can suggest is to turn on 'Internet session logs' (Internet Options) and check the result. There may be something in there which will help pin this down. (Don't forget to turn it off afterwards, and if you are going to post the output here, be sure to remove any password etc.)
I use IMAP a lot and occasionally have this problem which I put down to a poor connection or the server is very busy. The the last few deletes/moves are always reversed in that situation.