In the mid 90s I worked for a small ISV that wrote at GIS that ran on windows 3.1 (a 32 bit operating system that ran 16 bit processes (that could have 32 bit code segments))
One of our customer required perfect uptime, which was a problem with the GetTickCount wraparound described here
Our solution was to run under NuMega SoftICE [1] and once a month, or so, dispatch an engineer to the customer to simultaneously patch the kernel value for the tick count and also the expected value in our software (and also clean up various handle based cruft)
This worked for years. Unfortunately the engineer in question was also an alcoholic, so a particularly spectacular bender spoiled an approx 3 year uptime