print " $stuff" if ($config{'allowpaypal'} != 0);

but does not return to the next line of code:

print "$more_stuff" if (($buyit ne "") & ($bid < $buyit));
[download]

OK, so my hunch is that one of $buyit or $bid is being used uninitialized. It's hard for me to tell, since the code you were having problems with doesn't seem to exist in the longer snippet, but if you're basing your script on that I'm guessing that you're not using strict or warnings.
Perhaps if you follow the fifth of the PerlMonks Commandments (was: Seven Deadly Sins) the errors will become more clear.
There's more info on this in Use strict and warnings.

You can also add a few simple 'print "now i'm on line X\n" markers to watch the script progress, or try Using the Perl Debugger

Also, if you click on the title of one of your own posts, you can edit it, rather than posting a bunch of replies to yourself. Many monks mark changes to posts with update to make the changes clearer.