Error Message and Crash When Trying To Convert

I've been watching the forum since Version 8.44 hoping that others would have the same problem and a solution but it seems not.
Here's my problem...since 8.44 I've run into quite a few books that would give me an error message (calibre.exe has stopped working)and crash Calibre when trying to convert...even epub to epub. The error and crash would resolve itself if I turned off Heuristic Processing. The funny thing is 8.43 would do the conversion even with Heuristic Processing on. I was hoping that Versions 8.45 et. seq. would fix my problem but they didn't. With these versions I would get the error and then Calibre would crash to desktop also.
Was there a change in the conversion engine between 8.43 and 8.44 that would explain this? Or any ideas what could be causing this to happen with the newer versions and not 8.43?

If this helps:
Faulting application name: calibre.exe, version: 0.8.46.0, time stamp: 0x4f7e6778
Faulting module name: python27.dll, version: 2.7.1150.1013, time stamp: 0x4cf1405f
Exception code: 0xc0000005
Fault offset: 0x00013be8
Faulting process id: 0x1a40
Faulting application start time: 0x01cd17ab590e7075
Faulting application path: D:\EBooks\Calibre\calibre.exe
Faulting module path: D:\EBooks\Calibre\DLLs\python27.dll
Report Id: c3adbe5a-839e-11e1-8f5b-002354a19bf1