Folders unintentionally moved while browsing directory tree

One of our customers experiences that folders are mysteriously slipping away underneath another folder in the same subdirectory. This happens spontaniously when he's browsing the directory tree and clicking on various folders. Usually the topmost folder in a subdirectory moves underneath the next folder in that directory. I've investigated this and reproduced the problem with the following setup:

1. Drupal 5.1, WebFM 5.x-2.1, theme based on Amadou
2. Internet Explorer 7 on Windows XP
(Strangely enough I could NOT reproduce the problem with Firefox.)

Steps to reproduce:

1. Create a directory structure with a couple of folders and subfolders
2. Login as a user with "administer webfm" rights
3. Click on a folder in the directory tree
4. While the right panel says "working", click on another folder
5. Check the directory structure, mostly something has changed

Proposed fix:

Perhaps this is one of the "drag-and-drop" issues I've read about which seem to occur when using Internet Explorer. But since this happens without dragging something, I thought it might be possible to fix it.
Maybe it's possible to let WebFM ignore all clicks while "working" / processing a request?

Remco.