I don't recommend rushing to get a new cable (which is part # KHD-5L1, FYI), as that is only one of many things that could be the problem. It could be the cable, but it could also be a loose internal connection, or the Keg or even your head unit could simply be failing. There could be an electrical fault in your car. Depending on your location, it could even be too damn cold to use the Keg!
If you have any log files, you can post them and maybe Stuart or Sam or someone can decipher them. (If posting, use the "attach" option under "additional options" when replying rather than posting the whole log as inline text.)
If you know anyone else with a Keg/PB, borrow a known working DMS to test in your Keg. If you get the same symptoms, you will be sure that the problem is not related to the DMS. Likewise, you could test your DMS in their system.