attiny85 system clock prescaler

Hi, I was playing around with the internal RC oscillator and prescaler by adding the following code at setup of Blink:

CLKPR = 0x80; // enable system clock prescaler
  CLKPR = 0x05; // set system clock prescaler 32

The code worked well. After this, I am not able to upload the any sketch to this attiny85 anymore. This was the message I got:

avrdude: Expected signature for ATtiny85 is 1E 93 0B * Double check chip, or use -F to override this check.* Wrong microcontroller found. Did you select the right board from the Tools > Board menu?

Does this have something to do with the clock + prescaler? Anyone can help?

May be a stupid question, but did you remove power from the device and restore it? Otherwise the chip may be to slow to get the new code by synchronous serial. How did you set the CKDIV8 fuse?