Some web servers do not return properly formatted 404 HTTP responses,
which can cause the Java networking stack to confuse the HTML page
corresponding to the 404 with the bytes for a class file. This causes
a ClassFormatError to be thrown from deep within the Java Plug-In,
to the web browser and leading to a browser hang.
This issue has been fixed in the following ways:
- Explicitly catching the ClassFormatError at the point of failure
- Catching all Throwables, not just Exceptions, during attempted
returned to the browser for Errors as well as Exceptions.
- Explicitly disabling the codebase lookup for class loaders created
for so-called "dummy applets", which implement the "java" and
"Packages" keywords in the Firefox browser, so that we will not
make the round-trip to the server for bogus classes such as