Random errors: what can cause them

Windows or Report name length:
This one happens only under WinDev 5.5: if you name some windows or report with a name that doesn't follow the 8.3 old DOS size, when you call the window or the report, you can (execution time, of course) have a very nice effect: an error message telling you that a window or a report doesn't exist, but giving you the name of an existing one, not the too lengthy one creating the problem...

It can even tells you that a report doesn't exist when you were doing a window opening...

The good thing is that this happens on the line where the 'wrong' name is used, so you can pinpoint the origin of the problem quite easily.