problem with my "Check Control Display"

My pride and joy is a 1996 750il E38(I think) V12 with 80000km

I have a problem with my "Check Control Display"

Quite often it comes on withe the message "CHECK BACK UP LIGHT"
I've checked all the tail lights, back-up, brake & turn signals... nothing seems to be amiss.

In the meantime whenever I turn on the "Front Window Defroster" I can never predict whether it will blow full force HOT or COOL (it does what IT wants).

I also notice that the "Temperature Display" figures are sometimes missing some of their dots (not the same dots all the time) and that on the "Temperature Control Button" the blue triangular DOWN arrow does not light up (sometimes it flickers on and off faintly)...

Please HELP & Thanx in advance for any advice

OK, I finally spoke with the previous owner of my car and he told me that he also had experienced the problem with the "Check Control Display" telling him to check the back-up light... (it was supposedly a false reading... DA (from the dealer) nothing done to solve it)
So I'll start a new Thread re:the defroster