Ok,
I was probably being slightly vague, sorry.
The idea is not to overwrite a file if it is open but instead close it and then the program can continue. Basically if a user forgets to close the file and calls the macro again (called from another program), excel will stop, i just need it to continue - the file which the user would want would be the file that the user ran the program on, hence the old file is not needed.
Cheers