As chromatic mentioned, if you check out perldoc -f system you'll see the following interesting little tidbit:

You can check all the failure possibilities by inspecting $? like this
+:

    if ($? == -1) {
        print "failed to execute: $!\n";
    }
    elsif ($? & 127) {
        printf "child died with signal %d, %s coredump\n",
            ($? & 127),  ($? & 128) ? 'with' : 'without';
    }
    else {
        printf "child exited with value %d\n", $? >> 8;
    }
[download]

Perhaps the extra verbosity in this error reporting will help you narrow down the problem.