Problem with HyperCard Stack

Hello List,

I have used HyperCard for a number of years and am a devotee.

I have a stack which is loosely based on the address stack and
which has been working OK for some years.

Now, when I try to open it the watch hands move and then appear to go
backward slightly. I get an error message "unexpected error 160690"
and am unable to open the stack.

Can anybody help?

Thanks,

Bill