PageFair says that
22.7% of web surfers are blocking ads. Looking at a smaller subset of sites for the past 4 months, the company says that the use of ad blocking is
growing at a rate of 43% per year.
The thumbs on that site are named numerically, 5 digits
http://www.ptclassic.com/tgpthumbs/39119.jpg
think that may be what is triggering adblockers to block the thumbnails or maybe the 'tgp' in the directory name.
i had my banners in a directory named 'banners' - AdBlockPlus was blocking my banners, so i renamed the directory and that stopped them being blocked.