Hi Ayman,
right click on your autoexec.bat file and choose edit. At this point
you should see a line that looks like this:
set classpath = %classpath%;jdk1.1.2\jre\lib\rt.jar and one that looks like this:
path = %path%;jdk1.1.2\bin\ or something to that effect. You need to change these lines so that they point to the folder which stores 1.3 (the most likely scenario is that you'll just have to change
jdk1.1.2 to something like
jdk1.3.1 or whatever the folder name is in which 1.3 is located).
This might sound confusing but I hope it helps.
have a good one,
Paul