XML load works in IE but not in FireFox

I have xml-picture gallery and everything was working when i tested it. As soon as my client uploaded 100+ pictures, it stopped working on firefox. I discovered that when i use LIMIT to make mysql query smaller in xml file it works in firefox too, but as soon as query is larger, nothing happens. Everything works fine on Internet Explorer, not matter how many pictures there is.

Found many topics on the Ethernet but none of them related to the size of XML (or mysql query)

Looking forward to your help.

Thanks in advance!