I'm having problems with getting the thumbnails to show up. I've tried setting the permissions and have confirmed that GD image library is installed.

I've sent an e-mail to my hosting company and got this response:

I am sorry, but seems your script doesn't use the php function imagepng() correctly. Please visit the page:
www.coderemix.com/tutorials/imagepng-fatal-libpng-error
it will explain why the error appears and what your programmer needs to do to solve the problem.

Does anyone know if there is a fix for this?

Regards,
Michael