Rss help.

Ok ran into another problem. I been searching the help forums and havn’t found it. I am having problems getting the rss entries to work. I can pull up the rss page. or index.php?feed=rss. Thats not the problem. I am using a rss feed from another site that updates daily for posts and getting two errors that I don’t know how to fix. Withouth the rss feed from the other sites, it works fine. Cause I have wordpress on another blog and it works fine. The first error is

Cannot view XML input using XSL style sheet. Please correct the error and then click the Refresh button, or try again later.

No clue what that means or how to fix it and the other error is

A semi colon character was expected. Error processing resource (Gives URL)

Is there a way to make a rss page with semi colons? Really what I want to do is make a site map for google, yahoo and other search engines. But I don’t know if I can when I can’t pull up the rss feed page.

Any help would be great.