The following test script based on your sample works as expected. Maybe you can modify it to show the problem you see? Keep it as a stand alone test script though!

use strict;
use warnings;

my @strings = (
    "APPCRASH.",
    "he protected system file.",
    "EMET_DLL Module logged the following event:.",
    "your virus/spyware.",
    "A new process has been created\..",
    "A service was installed in the system\..",
    "A scheduled task was created\..",
    "Logon Type:[\\W]*(3|10).",
    "\\\\Software\\\\Microsoft\\\\Windows\\\\CurrentVersion\\\\Run.",
    "service terminated unexpectedly\..",
    "service was successfully sent a.",
    "service entered the.",
    "service was changed from."
    );

while (defined (my $info = <DATA>)) {
    for my $string (@strings) {
        chomp $info;

        if ($info =~ /\Q$string\E/) {
            print "Line # $.: '$string' --> '$info'\n";
        }
    }
}

__DATA__
APPCRASH.
nothing to see here
Part sentence: service entered the.
[download]

You can avoid the explicit loop over strings by constructing a combined match expression:

use strict;
use warnings;

my @strings = (
    "APPCRASH.",
    "he protected system file.",
    "EMET_DLL Module logged the following event:.",
    "your virus/spyware.",
    "A new process has been created\..",
    "A service was installed in the system\..",
    "A scheduled task was created\..",
    "Logon Type:[\\W]*(3|10).",
    "\\\\Software\\\\Microsoft\\\\Windows\\\\CurrentVersion\\\\Run.",
    "service terminated unexpectedly\..",
    "service was successfully sent a.",
    "service entered the.",
    "service was changed from."
    );
my $match = join '|', map {qr/\Q$_\E/} @strings;

while (defined (my $info = <DATA>)) {
    chomp $info;
    next if $info !~ /($match)/;

    print "Line # $.: '$1' --> '$info'\n";
}

__DATA__
APPCRASH.
nothing to see here
Part sentence: service entered the.
[download]