Constantly reading a log file from 3rd party application...

It baffles me why is everything ok but sometimes all of sudden the file handle becomes unreadable even there is a new data cosntantly added to it, the only solution becomes to close Auto-it process that opened the handle and re-open it again after relaunch.

So the procedure is simple

$xml = FileOpen("c:\path_to_file.xml")

while 1
$data = FileRead($xml)
consolewrite("inspecting data >"&$data&@lf)
wend 

But then all of sudden sometimes the handle just becomes undreadable and FileRead() returns blank even it shouldnt(new data is added constantly...)

Any other method i could try to avoid this?