MIS System Crashing - Date Error

Interesting error today - have seen this one before.

The MIS system would crash on startup, but only for a specific user and when I tried it myself it was fine.

It transpired that the computer was set to English (US) and so the dates were presenting in MM/DD rather than DD/MM. Since some dates are (historically) saved as text not as date format, it couldn't interpret them and crashed. We should, of course, change the system to save all dates properly, but the quick solution is to reset the user to English (UK).