So, the script is working now (after not working for a day) without ever being modified? Does the variable's value depend on input from the cgi form? Are you worrying that it might happen again? Were you hoping we could provide some answers, or just venting about something that seems inexplicable? (Is this too many questions, and we should just drop it?)

It could be interesting to know when this newest version of perl was installed on that server -- you could run "perl -V" in backticks and print the line that says "Compiled at ..."; indeed, print all the output, because there are many relevant facts provided there (e.g. whether your notion of "newest version" matches someone else's), and unless you provide at least some details of that sort, it's kind of pointless to give the appearance of asking for help.