I think you are right Seffens,
Have read the thread here: https://discuss.elastic.co/t/fatal-error-runtime-cannot-map-pages-in-arena-address-space/51250/20.
I believe the issue is due to the max amount of files opening in file beat windows 32 bit version. In our case one log folder contains 11337 files and another log folder contains 29911 files. For the first-time parse this is an issue due to Window memory allocation failure with max threads exceed single process handling limit in Win 32 bits filebeat version.
It seems the 64 bits version has this issue fixed and our team decided to give it a go and see how it's going.
Would like to hear from ELK team how this issue get fixed in 64 bits version and when the production version of 64 bits could be released in a near future.
Regards,
Allen