A) Yes.
B) A few MS development utils will modify the system so that when a program crashes, one of the options is to debug the program.
C) Then it you need to do more looking, because it broke somewhere. Try to reproduce the bug.
That being said, if you're using perl, your users will most likely be able to "pull up the script". There are very few ways you can prevent this.
Comment on Re: VB debugging my Perl Scripts on user comp? help! Security issue!