"Error Synchronizing with the board" message "Error Synchronizing with the board" message displayed.

So I downloaded "Pcode_hb.s19" with hbdl.exe. 
Immediately after, it seems to work well. 
But in several minutes, the icwin program says 
"Error Synchronizing with the board" again.
so I download again, HB works within some minutes, and
error. 

Does anybody have any advices? 
Replacement of CPU -68hc11- with new one can be a solution?

Thanks in advance.
