A game that I was in http://www.wargear.net/games/view/3875 the player was absent for 7 days, I added a vote to boot (which booted the person) and the turn timer said something in the ~14564 days, which seems a bit of an exaggeration :)

Upon revisiting the game this statistic is no longer displayed.

So it was only a temporary thing, i.e. straight after the boot occurred?

Yes, it was a temporary thing. However I did once see a timer in an expired game of ~126 days. Not a game that I was in, and a few weeks ago - not very helpful I know, I would normally have more information on a bug but I haven't been in a situation to duplicate it (and would rather not end games with boots anyways).