kmttg stopped working

I realize this is a vague problem, but there is no obvious solution at the moment.

I was happily running kmttg on Windows 7 (not installed as a service) for a month or two. But it has recently stopped working. When I click on the .jar file I now get a quick flash of the interface screen, it disappears and then nothing.

I tried downloading and installing it again, but I get the same issue. Should I be deleting the files or editing the registry to remove all traces before re-installing?