I looked at it, too, and agree that the problem is the inclusion of an underline tag on each of the URLs. There's an opening underline tag right before each link and a closing underline tag within each link.
I just double-checked in the database and it looks like you probably typed something like the following (without spaces):
[ u ] h ttp://www.jaxworks.com/calc2.htm [ /u ]
You can't use any formatting codes right in with the URL because it'll include the trailing one (unless there's a space) as part of the URL when it converts your input to an anchor ("a href=") tag.