4997 hours! I think the plane will have crashed by then. I'm in the middle of doing a flight now and it jumped from being just under 250 to just under 5000 hours in the space of about an hours flight time. Anyone else experienced this? Any cfg fix available?

You probably made the same mistake I did, thinking there was a single global service interval. In fact it depends on what system you are looking at - some have service intervals of 10,000 hrs!