instant messenger

had a few complaints from members about the IM on my site, well lets say X sends Y a IM and if Y goes offline and then signs in later and X aint online the IM box keeps following the page up and down and cant remove because X is no longer online and they only way to get if off is for both of them to be online, very annoying any help would be great

Can I see this?  I have never seen this problem before and would love a chance to view it. 

On my sites, I have people attempt to send IM's all the time and all they have to do is just decline the IM and it goes away or close the window that tries to open.