What kind of machines are these, size and what they generally do?
One type I frequently have this exact trouble with is exposers for imaging circuit boards.
A customer of mine has 12 of one brand that all when the machine is installed only runs for 30 days, then it shuts down. Each machine is $1/4 million.
Computers on these are replaced at the rate of about 2 per year and hard drives about the same - and those need a license right away, and getting a license from the OEM is a process. A license request file has to be created and sent in,
when they get around to it they run that file through their license generator and
ship a flash drive with the license through the post office,
Files commonly get corrupted and need reissued also.
Easily this customer has at least one machine down every day of the year for this, and I have seen up to 4 of them down and really effecting their production.
A stamping plant's QC dep't had a very similar issue with a lab machine frequently down for a license issue, and that was the only one of them they had.
EDIT: Years ago I had to work with an inventory system called DataFlex that had a corrupted annual license system. Fortunately that program was the one true victim of Y2K, it could NOT handle the 2 digit year 00 and crashed hard.