If you have an 8GB board, using 32bit is just crippling the board anyway, as they have to do tricks to access all of the memory.
The symptom Juanito refers to is Xorg is getting killed due to the kernel running out of memory, when doing things that have lots of disk activity, like mounting extensions.
If you still want to use piCore 32bit, then for now, its best to turn your 8GB board into a 4GB board by adding
total_mem=4096 in the config.txt file.
Note: this does not impact headless systems that do not use Xorg