I dont know if this a bug or just plain old bad luck.
I near to only drive AS National and about 10-15 times when im getting a good time roughly about 1.42.50 my game freeze up and sound loops.
It always freeze 100 meter after the last chicane and here is the funny part, it has NEVER frozen when doing a bad lap. My pb is 1.42.97 and on these freezing occations i estemate that the finnish time would be better than this, i measure this from the time when exiting chicane.

Have anyone ever seen this before or is it just me?
Very very anoying ecspecially when winning a race

you're too fast man. slow down , get a clue

seriously though it sounds very strange and annoying, did u try to mess with graphics settings etc (both driver and lfs)? i can't see how it's related, but worth a go imho.

no idea here, just a thought: Turn auto replay saving off.

Don't know if it helps but it would be easier to just slow down a bit

Join the club, look in the technical assistance section, there's a topic I opened a few weeks ago. Also a guy who says that lfs time isnt always equal to the real time. This might be the cause of these crashes.

http://www.lfsforum.net/showthread.php?t=3725
and
http://www.lfsforum.net/showthread.php?p=88417

(I know, it always happens when you're doing great in an importand race, or driving a new pb)

Well in short words, I had the same prob.
Turned out that my CPU Fan and my cooling ribs were dirty and thus hadn't their full cooling potential anymore. So in short words my CPU overheated. Not so much that the CPU would shut down, but only for LFS to do a CTD.

CPU: AMD Athlon 2800 XP+

I recommend less HOTlapping

It certainly doesn't have anything to do with the lap times you're getting... as it has been suggested already, I think it is more likely that this is a cooling problem. Does it happen only after a longer time of playing or is it completely random? Also, does it happen when there's many cars on track or isn't there any clue on this?