However if i try and copy the classes to a file on a network and open up the applet on another pc the applet opens up but when i press my calculate button nothing comes up at all. For some reason in the webpage it will not display text for some reason.
I assume that this PC is running IE using MS's Java VM. This VM is only compatible up to 1.1.4. Double.parseDouble was added later than 1.1, I think it was added in 1.2, but it might have been 1.3.
Change your Double.parseDouble() calls to something like Double.valueOf().doubleValue()
You might also need to compile using the "-target 1.1" option in Javac if you are using 1.3 or 1.4.