Yau,
I am assuming that by Fatal Error you are referring to an error that shuts down VFP (or your app if it is an exe). Those types of errors are hard to debug because they are a result of either VFP, ODBC, or Windows getting into a state that is unrecoverable and whatever (VFP, ODBC, or Windows) it is that gets in that state can't tell you what is going on because it is ready to crash.
Can you give any more detail about the error that is occuring (what is the exact message). Have you tried putting an AERROR(laError) just after the line that causes the error and then writing laError(1,2) out to a file for review? That will give you details about the exact error that ODBC has if that is what is erroring. What is the line of code that results in the "fatal error"? What is the error message related to the "fatal error"?