Ray,

Since fread is a library function it's unlikely to be the source of
the problem regardless of the optimization - I think you need to look
in your own code for the issue. It's more likely to be a real problem
that doesn't show up in a debug build. If you're using a recent
version of VS, be sure to debug with the run-time checking options
enabled - they may show a problem even in the debug build.

Dave

Yes, there is a problem reading files under Windows.

The only way it works is to turn off all optimizations, activate all
debugging information, link to MFC, and run it under the debugger.

P.S.  Just kidding.