I tried your stock ROM but it is unstable and crashes regularly (sometimes after hours or only after days). And this only because I decreased the cpu rate to 480 MHz. (otherwise I could not even boot it properly)
I reinstalled it (with TeamWin recovery) several times. No chance!
I cannot imagine that it runs stable on your WFS. I am quite sure that there is a bug of the memory management in the kernel 'RUU Marvel S' !!
Actually it is NOT the SD card or Data2SD !
Do you have any idea...
* what can be the reason?, or
* if there is an updated stable running version?, or
* if there is a tool that I can use to test to find out the problem?, or
* if there is another fitting kernel I can exchange this one with?
My telephone identity says: 'HTC Wildfire S A510e'.
My SD ard partitions are well configured (e.g. all are primary, etc.).
Does it might help to use the 'cake' kernel? I have read anywhere about it...
Thank you so much for any useful advice!
Best wishes to you.