make sure file record is write to the hard disk

hi.

hi need a monitor to my functions calls in vb app.

i do it to see the last function call when the app crash.
(im debugging...)
the problem is that when i write to file, the records are write to the memory and then write to the HD.

my q is:

how can i write record to file and be sure 100% its in
HARD DISK.
AND THEN IF APP IS CRASH I KNOW THAT ALL THE RECORDS R IN THE HARD DISK.

in short way: is there way to flush buffer to HD AFTER writing record.

thanks and goodbye.