91 Eagle Premier clock displays Er4

I have a 91 Eagle Premier that suddenly started showing "Er4" on its clock and it cannot be cleared with the clock setting buttons.
Does anyone have any idea what this code means? I have a Chilton's manual for the car but it makes no mention of codes on the clock display.
Any info greatly appreciated.
Thanks.

Try unhooking the battery for abit, that may reset the clock.

I disconnected the battery for 5 minutes and then reconnected it.
That seemed to fix the problem.
I was able to reset the clock and now it all seems to work OK.

Thanks for the tip!

cool!!!!