Larry, Ed

First of all thanks for your replies.

Well, I'd already did the that function and it works reasonably well (there is a fluctuation of +1/-1 secs, but is ok for me because I don't need more accuracy than that) and is also reasonably fast (it checks the gap in .005 secs).
The problem with this approach is: the function that needs that info (it checks that several other programs are running, issuing a warning if they're not) is called many times per second. But the same function can be called from other programs just once or a random number of times.
I can solve this problem passing a parameter to tell the function if it must get the gap, and then each caller program can take the proper action (ie. only ask to check the gap every n seconds/minutes/hours) But in order to accomplish this I must rebuild various projects, something I wanted to avoid.
Anyway I think I will take this approach on monday and close the case.

Thanks again, and I hope that what I wrote is clear, I'm not convinced I can understand it!

Hugo