I have attached a *simple* test case which loads a class from a jar
file (test.jar).  All the components involved (JRE, *.class, *.jar) are
located on a network mapped drive on a Windows 2000 system. JRE version
that was used was 1.4.2_03.

When we run this program, the classloader loads a class "Test" from
"test.jar" file. It will continue to load this class for 5 iterations
for every return key pressed, followed by loading a second class
"Test2" in an infinite loop (again with every return key).

The problem here is if we remove the n/w connectivity between these
interations and *restore* it back before trying to load the same/next
class. The program will abort with a "classnotfound" exception. 

IMP: The problem is observed only when the JRE is also installed on a
n/w mapped drive.

Interestingly, on one of the Windows box that I verified this problem
with, the native OS restores the access to the offlined n/w mapped
drive *automatically*. So, in theory, we should not have had problem in
loading class files from the jar file.

A new version of the program "Loadernew.java" just lists the directory
contents and it resumes listing the files and never throws any
exception after the n/w connectivity is *restored*.

So, the problem seems to be specific the Java side components related
to the "Classloader" mechanism.

I wrote a simple Hello World C program and copied the resulting "exe"
to the n/w mapped drive. I did not see any probem when I disconnected
and reconnected back the n/w cable while the program was in action. Of
course, the "java.exe" is more complex and will have dependency on
other DLL's which are also located on the n/w mapped drive.