Hm. Which versions of what on what platforms? What size and types of files when it fails? Any other pertinent information besides "the script ends"?

I set the following going. It picks two files--from a few hundred bytes to 25MB; source files, text data; binary data; images; video--at random, and feeds them to your script (modified with warn instead of print for informational messages):

perl -E"@f=grep{ -s $_  < 25e6} glob'*'; $p = system qq[junk10 $f[ ran
+d @f ] $f[ rand @f ] >nul] for 1 .. 1e3"
successfully opened up . junk48.pl
successfully opened up . 800691.dat2.png
Done [800691.dat2.png junk48.pl]
successfully opened up . IC-junk1.pl
successfully opened up . 834245.13
successfully opened up . 797136-a.pl
successfully opened up . 2x1e5+2x20.dat
Done [797136-a.pl 2x1e5+2x20.dat]
successfully opened up . smallints.txt
successfully opened up . 8828831.trc.txt
Done [smallints.txt 8828831.trc.txt]
successfully opened up . Service.pl
successfully opened up . 759033.pl
Done [Service.pl 759033.pl]
Terminating on signal SIGINT(2)
[download]

It completed the 1000 pairs of files in a few minutes with no apparent failures, which I take to mean that there is little wrong with the functionality of the code (on my system & versions).

So, then I thought about how could I make it fail, and fed it a 4GB binary file that contained no newlines and watched as the memory grew and grew, and the IO rate dropped & dropped until it ran the machine out of memory and died silently. The last messages displayed were the two "successfully open up" messages.

Does that fit your symptoms?