Loading XML of significant size

I need to load an XML which has reference to external DTDs. The referenced DTD internally references other DTDs. When I try to load the XML in XMLTextReader, I get an Index Out Of Bounds error on the line . The version is .NET 1.1. On googling, I got that in 1.1 max 2 GB of XML data can be processed by XML readers. But, my data doesn't seem to be more then 2 GB. 

Any help would be appreciated.

Regards
GS