Welcome to The Elder Stats.
This thread is months old because no one has reported having this problem for a while. The rest of the site is fairly active, but certainly not dead. I suppose more people use the character profiles part of the websites than the forum part, but that may change in the future.
Anyway, I'm going to have to really take a look at what is so buggy about this script. For some reason, it works like a gem for me and others without a problem, but for some people it gives the error that the format is not accepted. So, you are saying that it will allow .GIFs to be uploaded, but not .JPGs or .PNGs? Those all work for me, but I'll check into this issue more this weekend. I'm sorry about this. I'll try to get this fixed.