WTF weird SLAC problem?

I have the SLAC.rar file, and I extracted it to My Documents, opened it registered etc and it worked fine. Didn't use it for a few days. Now I come to use it, and woop, I click on the .exe and it disappeared, with a message "Cant find SLAC.exe make sure u typed correctly blabla"
I still have the .rar file, so I try to extract the SLAC.exe, but nothing will happen, it shows the extract box, appears to work, but it won't extract the SLAC.exe WTF!