There is one other thing you can try. You mentioned that inclusion of vendor jars triggers this. You can see if Class-Path entries in the manifest of these jars contains references to non-existing jars. Tldscanner used to throw exception when this happens. This has been fixed, but you might be using a older version in 3.0.1. You can either edit the Class-Path in the manifest to remove bad entries, or download the latest jasper from
http://download.java.net/maven/2/org/glassfish/web/jsp-impl/2.2.2-b03/ and drop it into <gf>/modules/ (after renaming it ot jsp-impl.jar).
Good luck!
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