The server log is clean, sadly. It simply stops logging after a crash. And yes, we've thougth about this being related to wireless redstone, and we're in the midst of hunting down any placed objects related to it. I'll see what i can do about a Java reinstall, but as i do not have full access to the server, I'll have to wait for the people running the server park to have time to do so.
Thanks for the help so far, will update if things work out for the better, or worse.