I got the checkered page when the system could not be read (I tried to format the internal drive as ext2 but it did not work).
If this is the problem the easiest way to solve it is to get the firmware reinstallation instructions from Bookeen or from somebody here.
Otherwise you could try to mount the internal drive when it hangs and copy your backuped system files to it. If that does not work you can reformat it and then copy the files back.
If you use linux and need to repartition it then create one partition and set the type to "b". Then use mkfs.vfat to build the file system.
If you do not have a backup of the system files here they are both for the original firmware and for the latest build:
http://egad.dyndns.org/cybook/