Question : Problem: Switch Crash while copying IOS

I have a cisco 2950 switch .The switch is in use  and i want to backup it's existing IOS.

Whenever I try to backup  using TFTP the switch hangs after sending XX MB of  data and i
have to reboot the switch to make it work again.

I tried it twice and it appears to have hung at the same place.( from the progress bar)

If try to do copy the config it just works fine. Does this mean i have a bad block on my switch flash ? Would formatting the flash will help ? What are my options ?

Answer : Problem: Switch Crash while copying IOS

We finally replaced the switch.