Other monks have given you some good advice about line endings but I've seen the 'bad interpreter' message reported by the bash shell on a Solaris box - it was purely a permissions problem:

$ ls -l foo.pl

-rw-r--r--   1 user group     44 Jan  9 00:05 foo.pl

$ ./foo.pl

bash: ./foo.pl: bad interpreter: Permission denied

$ chmod 755 foo.pl

$ ls -l foo.pl

$ -rwxr-xr-x   1 user group     44 Jan  9 00:16 foo.pl

$ ./foo.pl

$ Hello World

$
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