Problem with llama book script

[Customer Service]

O enlightened ones, here is my question:
I am going through the llama book  (which, by the way, is the most useful
tool
I have bought so far for perl reference) in order to learn perl.  On page 10
is a simple script which I copied and have attempted to execute for the last
1/2 hour.  Please tell me what is wrong!
I'm using ActiveStatePerl5.6.1 and Apache web server on M$ win98se.

##############perl script   file name: gradation.pl ##################
#!c:/perl/bin/perl -w

open(GRADES, "c:\perl\eg\grades.txt") or die "Can't open grades: $!\n";
while ($line = <GRADES>) {
        ($student, $grade) = split(" ", $line);
        $grades{$student} .= $grade . " ";
}

foreach $student (sort keys %grades) {
        $scores = 0;
        $total = 0;
        @grades = split(" ", $grades{$student});
        foreach $grades (@grades) {
                $total += $grade;
                $scores++;
        }
        $average = $total / $scores;
        print "$student: $grades{$student}\tAverage: $average\n";
}

##### my text file is as follows, and is called "grades.txt" in same path as
gradation.pl

Noel  25
Ben  76
Clementine  49
Norm  66
Chris  92
Doug  42
Carol  25
Ben  12
Clementine  0
Norm  66
...

# Resulting error messages

Unrecognized escape \p passed through at c:\perl\eg\gradation.pl Line 3
Unrecognized escape \g passed through at c:\perl\eg\gradation.pl Line 3
Can't open grades: No such file or directory
######### That's it #########


Thanks for any help.
Standing by with a water hose,
Nathan