"make sure your RTC timebase is a timer with auto reload. Anything else will give you slight imprecision in the timekeeping."

This just is not the case. We already flogged this horse to death, barbequed it and ate it in these threads:

http://www.8052.com/forum/read.phtml?id=56716

http://www.8052.com/forum/read.phtml?id=42249