I've encountered this problem in 5.5.1 version. I don't know if I have fixed the error with this steps:

1. Reinstalled AutoIt but I have installed it in x86 version for more compatibility
2. Compiled the script (x86)

I'm using my bot in windows 7 64-bit.. I've been using 5.5.1 for 8 hours now with no error..Hope this helps someone who encountered this error.. Good day everyone! Kudos to the Devs for this wonderful update!