Yes I believe you're right about it thinking the coordinates in the G-code program are too big for the machine though it might be that none of the currently included posts are compatible with your machine. It shouldn't take more than a few minutes to get one working if that's the issue. Do you have any G-code that you're able to run on your machine that I could look at as a reference? It doesn't matter what program produced it - just that it runs as expected on your machine. The problem could simply be that none of the existing posts in v1.43a are formatting the G-code to where your controller is able to properly parse out the command blocks and it could be interpreting a non-coordinate value as a coordinate.
You can use Pastebin.org to put the contents of a G-code file online and reply with the link it produces for me to see. I'll then put up a post for you to download and try out :)