To ensure it was not our code causing the problem I requested a user use the following demo page from your site to try and duplicate the issue:

http://cutesoft.net/example/Multiple.aspx

 

The following is the behavior that was experienced:

 

The user copied text into the first editor from word multiple times.

After ~3 copy/paste iterations, upon requesting to paste (ctrl^v) from word the user got the prompt for if they would like to clean their text .

The user clicked ok. It pasted as expected. When the user then clicked on the second box the browser stopped responding. 

 

OS: XP

Browser: IE 6