When your brother saved it in Linux it was probably the file permissions. Can you run the code form the command line in windows? If you are editing in windows and putting it back on to the Linux server check the file permissions (ls -l) . They should be -rwxr-xr-x. In windows I think there is a utility called calcs to query/change the access control list of the file. If the web server can’t run it then you need to change that.
Your life, and finding a code problem in this script if it is indeed a code problem would be much easier if you were A. Using strict B. Using warnings and C. using CGI.