XHTML gives an error

Hi.

I tried to capture some information and data from online XHTML file
using XSL. But there are few error before the file can be processed.
Maybe because of the html file. So i try to clean the xhtml file and
still face the problem. Currently, I'm using Tidy, but still face same
problem.
Does anybody know how to clean any XHTML file or to convert into XML.
If I have the XML, the it would be easier for me to use XSL.

The page that I try to convert is
http://tools.cisco.com/security/center/viewAlert.x?alertId=18261
Basically I want to capture some information from the file such as the
value for the CVSS base and CVSS temporal.

Thank you

Regards