Remove Pipelining before Deletion,whether or not it removes it automatically or not I don't know,I have suffered a few problems with WLM but not this mentioned item,might be an idea to check if there is an update for Windows Live Mail just a thought..
The new MailWasher 2010 update 1.0.10 might cure it,or you can use this link to download it again which might solve the problem.
http://www.microsoft.com/downloads/deta ... laylang=en
