Maybe your problem is just that a 32-bit signed integer cannot hold the value 3759263696 (too large).  In other words, if you use a signed int as in

my $hex = "d0cf11e0a1b11ae1000000000000000001000000feffffff00000000370
+00000ffffffff";
my $bin = pack "H*", $hex;

for my $val (unpack "l<*", $bin ) {
    # last if $val == -1;
    print "val=$val\n";
}
[download]

you'd get

val=-535703600
val=-518344287
val=0
val=0
val=1
val=-2
val=0
val=55
val=-1
[download]

while, if you use an unsigned int (i.e. "L<*" in unpack), you'd get

val=3759263696
val=3776623009
val=0
val=0
val=1
val=4294967294
val=0
val=55
val=4294967295
[download]

but then you can no longer test for -1 as the stop condition...

Update: added "<" modifier (Perl 5.10) to the unpack templates (=force little endian), so the sample code would also run correctly on big-endian machines (note that for "L<" you could also say "V", but there's no respective equivalent of (signed) "l<")