I opened a .class file. . .

I'm going to use a word document as an example:

1. Browse to the file
2. Right Click on the file and chose "Open with"
3. Then click "Choose Default Program"
4. Make sure that the box is check like below and find the program you want to use to open the file

For Windows XP users:

1. Browse to the file in Windows Explorer

2. Right click on the file

3. Left Click on "Open With..."

4. Find the program that you want to make the default

5. Check the box shown in red below to make it the default

Try this. Create a copy of the file in the same folder as the original. Under folder options make you have view extensions enabled. Right click on the copy and click rename. Change the extension to .class. Good luck.

.class files (as far as I know) usually means that it's an Java Class file. Try making a batch file with the following code

@echo off
java [NAMEOFCLASSFILE]
pause

Make sure NOT to add .class to the name of the class file

If nothing happens than at least you know it isn't a Java Class file.