Unable to go to next page

Hi everybody,
i have a reccurent problem on my PBTL (1st version - 4.4 firmware),
the reader often gets stuck on a particular page,
and doesn't wants to go to the next one. It refreshes the current page, the led blinks but i'm still on the same page, no matter how many times i hit the button or touch the screen.

I don't think it is due to a particular format or text formatting option as i have all sorts of ebooks from various sources.

The only solution is to go 10 pages further (long press on the button), but i then get lost if the text is reformatted and zoomed in for example. It's really annoying.

Any of you experienced the same problem ?

Thanks a lot if anybody can help...