program hangs when a large file is read via file io

Hi,all
    I am working with DM6437 EVM. A file io mechanism is provided
on the demo program. When I read a large file such as 3x1024*768,
program hangs each time. I find that program hangs in the routine
named recv. If I read a small file, it works well.

   Recently I reinstall my computer system. Before that, the program
is Ok, even when a large file is read. But after intallation the same
program doesn't work. I am confused with that.

Best Regards
Jogging