Java HotSpot Virtual Machine

I have had to write a new Java Applet that can be operated using the Microsoft JVM (version 5.0.0.3810) under IE6.0

My problem is this...

I have two machines both with Windows 2000 Professional. Both machines have IE6.0 SP1 and the same version of JVM (listed above). My applet works the first time on both systems but then when I relaunch it it works on one and the browser hangs on the other (finally after a while produces an error message). This is the error...
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java.io.IOException: 192.168.0.6/test.asp
at com/ms/net/wininet/http/HttpInputStream.connect
at com/ms/net/wininet/http/HttpInputStream.<init>
at com/ms/net/wininet/http/HttpURLConnection.createInputStream
at com/ms/net/wininet/WininetURLConnection.getInputStream
at com/ms/net/wininet/http/HttpPostBufferStream.close
at java/io/OutputStreamWriter.close
at com/wul/lms/client/APIAdapterApplet.HTTPRequest
at com/wul/lms/client/APIAdapterApplet.GetParam
at com/wul/lms/client/APIAdapterApplet.LMSInitialize
java.io.IOException: 192.168.0.6/test.asp
at com/ms/net/wininet/http/HttpInputStream.connect
at com/ms/net/wininet/http/HttpInputStream.<init>
at com/ms/net/wininet/http/HttpURLConnection.createInputStream
at com/ms/net/wininet/WininetURLConnection.getInputStream
at com/ms/net/wininet/http/HttpPostBufferStream.close
at java/io/OutputStreamWriter.close
at com/wul/lms/client/APIAdapterApplet.HTTPRequest
at com/wul/lms/client/APIAdapterApplet.GetParam
at com/wul/lms/client/APIAdapterApplet.LMSInitialize

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Note that Sun's version of Java works everytime - however my client I am building the applet for can not use it because of old software they currently use that will not work on the latest build of Sun's Java. Makes you wish people would just use Sun's version which is up to version 1.4.x where the Microsoft version is based on 1.1.x

I am new to Java so I am not up with all the versions and compatability issues.