Problem with Javascript file downloaded

Hi everyone

Im totally new to downloading javascript files, and ive made a bad mistake when installing.

I downloaded a javascript file called 'close window' to my desktop then installed it using the
DW extension manager.

I thought after it would be a good idea to put that file then into a javascripts behaviors folder in my program file for DW. Bad idea!

When i loaded up DW8 again, i got lots of error messeges (which i can post if its any help) and now i cant use any javascripts.

Ive deinstalled the program and reinstalled the program many times. Ive tried deleting all my personal files i created as well, the reinstalling DW*

still the same messeges come up, ive been battling with this for 3 hours now, please someone help!!

thanks