I am experiencing the same problem that others have reported on this topic.  I explicitly set my Tomcat classpath to be sure of no redundancies in the jars.  I have a Tomcat startup batch file with one line that adds in all the jars in my WEB-INF\lib to the classpath explicitly.  When I comment that line out, I get the classnotfound errors.  When I put it back in, my web app runs fine.  Obviosly I want the line commented out and have the jars picked up in the lib dir, but that aint happening.
Because the jars work when explicitly included in the classpath, I conclude that the jars are not corrupt.  I also conclude, based on commenting out the explicit lib jars classpath, that there are not redundant jars in the classpath.  I have also checked other sources for possible classpath jar redundancies and I am just not finding any.
 I am running under Win2000 using jdk1.3. 
These is the exact dir structure I have set up:
I have gone through Craig McClanahans list of things to check and all seems to be as it should.
Any hope for a fix?  Should I continue to look at my config?  I have heard some people talk about setting up an explicit context for the app in the server.xml.  Does this solve the problem consistantly?
Bill Pfeiffer