Image caption with underline in ie but not in ff

Hi
I have a small problem with the depiction of my caption. On some pages (not on all) the caption text is underlined but only in the internet explorer and not in firefox even if i clearly define in my css not to do this
image-caption {text-decoration:none !important; }
What is even more strange is, that on some pages the caption text has an underline if i hover with the mouse (ie only) and other pages are absolutely correct.

The strange it is the more strange it comes: When i comment out each css line with text-decoration:underline;
in my style.css nothing changes at all.
I would be very thankful if someone could help me because it looks a bit ugly in ie, which is unfortunately a very often used browser.

Cheers