Problem recording large files with snack

[klappnase]

I am trying to develop some little sound applications for linux with
python using the Snack toolkit (I am far from being a "professional"
programmer, I just do this for fun and I am afraid that I'm still a
beginner).
Now I have this problem when I want to record large wav-files that
every time a screensaver starts up (or other programs are started)
there is a loss of audio data in the recording, so for example ten
seconds are completely missing.
The way I start recording is something like:

s = tkSnack.Sound(encoding="Lin16", frequency=44100, channels=2,
    fileformat="WAV",precision="double", byteteorder="littleEndian",
    file="xyz.wav")
s.record()

The "buffersize" option does not seem to have any effect on this
problem.
Does anyone know how to fix this?