This is what happened: I wrote a perl script using TextWrangler and managed to change the encoding to UTF8 BOM, which inserts te BOM marker at the start of the file. Perl promptly misses the #! and mayhem ensues. It then takes me the better part of an afternoon to figure this out since most text editors do not show the BOM marker even with various "show invisibles" options turned on.

Now, I've learned my lesson, I should have used less immediately, etc. etc.. What I'm wondering though is whether there is a text editor out there that lets you see every single byte of the file, even if they are "invisible"?