Tomcat server in Eclipse errors on web.xml

Hi

I'm new to JSP/JSF & Richfaces & Tomcat.

I currently have a project checkout out locally and have tomcat configured in my eclipse installation to run my project.

Now the following message seems to be randomly occurring when I start tomcat from eclipse:

"cvc-pattern-valid: Value 'head' is not facet-valid with respect to pattern '($||\p{L})(\p{L}|\p{Nd}||$)*' for type 'null'."

I originally thought it was when I was making changes to my web.xml file. Mainly because when I would go back and undo a change I made, the server would start up successfully.

But sometimes it seems that this error will be thrown, I will make no changes, come back 10 minutes later and start the server and it works fine!

Any ideas?