I was afraid of that, they are leaking signal, causing the other LED's to become erratic.   That is also a problem with the 555 timer chip.

To me this chip is the easiest one to get blinking lights out of.  One capacitor, one resistor, and you have it.  No resistors on the LED's, no crazy wiring.  Real simple.  These chips are cheap too!  Look on Ebay, you can get them from anywhere from $0.50 to $1.00 each.