[Zzed]

That's because the image is 256x170 which is smaller than your 320x240 image resize.

in dothumb()

Replace this:

    if(($img_info[0] <= 80) and ($img_info[1] <= 60)) {
      $code = "<a href=\"$code\" target=\"_blank\"><img src=\"$code\"></a>";
    }

with this:

    if(($img_info[0] <= 80) and ($img_info[1] <= 60)) {
      $code = "<a href=\"$code\" target=\"_blank\" border=\"0\"><img src=\"$code\"></a>";
    }

Excpet that instead of 80 and 60 you would be using 320 and 240 in the if statement.