No ticket specified error when submitting comments/replies using IE 6

Users who are attempting to add replies or comments to tickets using IE
version 6 are having the browser hang and no action is made. In the error
log the following message occurs at the same time:

No ticket specified () (/opt/rt3/share/html/Elements/Error:53)

This is RT 3.0.6. We do not seem to have the problem using other browsers.
Unfortunately, IE v6 is the standard browser at our site. We’re getting
lots of complaints from users who want to roll back to RT v2.