DM 15L keypress problems

[rflesch]

UPDATE: I reported the "fast-type" keystroke loss issue to SwissMicros. They suggested that I remove the battery and short-cut the calculator. I'm happe to report that this simple step removed all problems regarding lost keystrokes immediately.
I know it's the very first thing I should have done before going public with this issue, but I thought it's a firmware problem, similar to the random key press losses that are observed with firmware v16.
SwissMicros is a company with excellent customer service.
Roman