The process android.process.acore has stopped unexpectedly.

Problem: Error keeps repeating on Prestigio PMP5100C

Forums on web suggest factory reset, however keyboard is not responding, or respond only by clicking on message, then returning again.
It helped to reset it, and turn off few times, all of the sudden it started to work so far to reach settings and factory reset option - after erasing everything it worked ok, suggesting it was caused by some faulty software.
UPDATE: Possible cause of this problem is google,
in the first instance it was google mail application, and in another it was google talk. In both instances, applications were instaled as incorporated third party software, sw run fine until google account was added.

The second time it happened, it helped to draw android status bar - which was only possible action - down, open application remover software which was installed and luckily enough run in status bar all the time - and deinstal app associated with google. Once removed, error message stopped.

UPDATE 2:
The solution is to open setting- applications - and to click one by one and to clear cache on each of them, unistalling the last unused applications as well. Once the newspapers cache was cleared, repetative error miraculously dissapered.