Help needed with 74hc595

Hi All,

I'm using 74HC595  ICs for controlling 65 seven segment digits. Each digit is connected to a shift register and 65 such combo are fed in series. Scanning is employed to reduce power consumption. I'm using AVR Atmel Atmega8 for pumping data. The system worked perfectly with 74hc595 from ST but later when I used Ti Is, it started showing unnecessary flashing. Any one having some Idea what might be the reason? If you want more details about the hardware setup, please drop a line.

Thank you in advance