How do I clear upload buffer?

I am trying to create a web page which will allow the user to upload up to 3 files and store them in a SQL database.  I am using the fileupload control with runatserver set to true.  My upload seems to work some of the time but I think I am having some buffer issues.  Remember reading somewhere that the buffer should be cleared between transactions but have no idea how to do that. Whenever I try to upload an additional file I get the DNS can't find page response which indicates that my filelength is too large which leads me to believe that I have a buffer problem.  Have tried numerous times to make this work with no satisfaction that it can be deployed with any hope of success.  Need help fast!