Thanks for getting back to me - I've not got a computer running linux to test it on at the moment, but the following steps were recommended to me as a good starting place:
- Right-click the X86_64 file
- Select Properties
- Click the "Permissions" tab
- Check the "Allow executing file as program" checkbox next to "Execute"
Let me know if this helps in any way, if not I'll see if there's anything else