First of all, due to a problem with the checksum program in 4.2B, KETA02 will give you an "ERR" message even if the checksum is correct. if it says OK, then you still have a problem. The correct Checksum is "88F51049".

regarding the alltabs test, it takes a few goes as you have to press both buttons at exactly the same time.

There should only be one alltabs.tab in the root directory. I am unsure how it is possible that two files of identical names can exist together and I did not think it possible? Because I do not fully understand the situation I recommend that tomorrow you call your distributor for advice.