socket receive timeout not accurate

[fborot]

hello
I am trying to use the socket receive timeout property but I find it not accurate, there is an offset of 500 ms.
example, I set it to 500 ms, send the bytes, set the socket to receive and if that times out then I try again. the problem is that instead of timing out at the time I set it it does it 500 ms later. example
if value 500 ms, it does it at 1000 ms,
if the value is 1000 ms, it times out at 1500 ms later
and so on. I am including a little program in C#, Net 3.5 that shows what I say
have somebody seem this before, is there any other thing that I have to do before? I tried also setting other options like expedited, nodelay etc but they do not seem to work either.
Thank you in advance
fabian