Comment 1 for bug 746745

I am unable to replicate this. I tried converting 334 books in windows XP. While the memory consumption of the calibre-parallel.exe process often rose substantially (this is the worker process in which the conversions actually take place), the main calibre executable's memory consumption stayed below 120MB throughout (started at 95MB), and all the books were successfully converted.

 I suspect your crash is caused by the presence of a few bad books causing a memory leak and crash. I would suggest converting in smaller batches till you identify the bad books. If you are able to identify the books causing the crash, attach them to this ticket and I will see if it is possible to fix the leak caused by them.