>>Did you mean on Me, with "Bela"?
>
>Yeah, I thought you might be one of those that know :-)

Dear Mike,

unfortunately, I only suspect the following:

with timers you cannot get more precious watch than the system own watch.
It is because the timer events fired with a certain uncertainity. So if, you setup a timer with 1 sec interval, and add 1 to a variable in each event, the uncertainity will be summed. It means that the timing error will be summed.
(If the timing error has normal distribution with zero mean value, of course it will be zero, averagally)

bb