Posting code, particularly line 325, would be helpful. What is happening is your syntax is telling the interpreter to think the string is supposed to contain a symbolic reference (see perlref). One possible way you may have done this is the code ${$string}. If the content of the string is "0" at that point, the symbolic reference is interpreted as a reference to the variable $0, which I strongly suspect you did not intend. I would likely be a very good idea to leave use strict; in effect and fix what is likely a typo in line 325.