@DanBerdovich, Sven RK
I have been using Excel 2010 for about 18 months since the Technical Preview and have not had this problem, so I would suggest it is not a case of "why can't Microsoft fix this " or "this problem has not been resolved" but rather:
"no-one seems to be able to pin down a common cause as to why a handful of users have this problem and many thousands do not".
I have not had any reports of this from any of my consulting clients or training delegates, so I really don't think we can claim this is a universal bug.
I have recently had a strange problem with my laptop recently where it would work as if a Shift key was stuck down after waking from sleep mode. This would cause all sorts of problems such as selecting multiple cells (as wall as all sorts of other undesirable
behaviour). It is these sorts of external factors which may be part of the problem here, or of course it could be the bahaviour of some add-in or other issue.
Are you sure that you do not have "extend selection" or "add to selection" mode turned on (it would sho this in the status bar)? Have you tried turning extend mode on and off again? (F8, F8 again)