The while loop uses $_, but doesn't localize it. $_ is aliased to a location in @suffix. Thus, the location in @suffix gets overwritten.

One way to solve this would be to localize $_:

{
    local $_;
    while (<DATA>)
    {
        ...
    }
}
[download]

Another way would be to use a different variable on the foreach:

foreach $suffix (@suffix) # Or $s, or maybe use @suffixes
                          # or @suffixen to imply plural...
[download]

Also note, just for clarity, that DATA is a special filehandle opened to the source code after the token __DATA__. It might be a good idea to change that.

HTH...