Should have mentioned – one way I used to get around it was this:
Quit AE
Quit all other apps, and end task on any non-essential processes that are running.
Restart AE
Export as an Image Sequence
If it crashes, go through the steps above (possibly rebooting the PC too), then carry on from the frame where you crashed.
If your sequence includes audio, then export that seperately as a WAV
Stitch it all back together using QuickTime Pro 7.
It’s a right pain.