A good exercise when you're faced with a problem like this is to make a copy of the script, then eliminate as much non-related stuff from the copy as you can. Work towards the smallest script you can that still exhibits the problem. Many times, during the course of this exercise you'll get the "D'oh!" moment where the problem leaps out at you.

Then consider using CGI instead of 'cgi-lib2'. If cgi-lib2 is related to cgi-lib, then you're using an old, unmaintained module. CGI.pm is a safer choice.