Which samplerate are you running?
At which sequencer positions have you looped the song? How long have you looped the song before it starts freaking out?
Do you maybe have some sort of Powersaving features enabled in the bios or windows preferences?
hi, i think i found my probleme
my laptop have a trouble with the temperature of the CPU.
It always at 68°, and when i use renoise and replay a music it going to 90° !!
and at this moment the sound is crap and the cpu are blocked to 99%.
i’ll try to repaire this, i’ll say you if it work better after
Very nice song indeed! 
I Appreciate using of internal FX, pattern commands, authomation envelopes, and instrument FX, like filter envelope etc.
Playing here: 20-30 % CPU in renoise.
The best might be if you contact me by mail. There must be a solution for this which we could try to find in a icq session.
One more thing that you might try out before: As proposed somewhere else in the forum: Have you tried disabling the Hyper threading in the bios? Also make sure that no kind of energy saving is enabled in the bios and Windows settings.
Ah, and maybe its the same problem that MED had: Try do download a CPU temperature tool. Sometimes a tool for this is included in the software package that came with your computer. If the CPU overheats, it could cause things like this (and also crashes out of the blue).
thanks to all who have tried to help me with this issue.
So far no solution has been found.
I will check the temp of my machine and get back to you this wknd.
peace!