We have the same information. Microsoft's implementation rolled over at 49.7 days (2^32/(1000*60*60*24)). Microsoft's RPC uses GetTickCount(). Pre-fix implementations (Update Rollup 1 for Windows 2000 SP4 last year fixed it) would grow to use 60% of processor resources after the GetTickCount() rollover, killing system and network performance.
Because of this, the machine would become unusable if the FAA didn't reboot often. Harris put in a reset routine when the OS hit 49.7 days of uptime as a safeguard against the slowdown. So you get shutdown instead of slowdown.
It still amazes me though. Microsoft didn't think anyone would want to have their server up for 50 days at a time?
That sounds like the wisdom of experience.