It looks like
MemoryError: PermGen space java.lang.OutOfMemoryError: PermGen space
is a common problem. You can Increase the size of your pe
Which version of Tomcat are you using? Tomcat 7 and 6.0.30 have many features to avoid these leaks, or at least warn you about their cause.
This presentation by Mark Thomas of SpringSource (and longtime Tomcat committer) on this subject is very interesting.