redsn0w always crashes

[tuna]

I am trying to jailbreak my old model 3GS with 4.2.1 firmware. I have tried 0.9.6b4, 0.9.6cr8, and 0.9.7b4 versions of redsn0w, and all have the same symptoms:

After restarting my iMac, I will be able to run redsn0w once until it will get all the way to "waiting for reboot", and then it will display "unexpected error" and the jailbreak will have failed. And if I try to run redsn0w subsequent times without rebooting my iMac, it will crash almost immediately after the jailbreaking starts and bring up an error window.

Any ideas?

 

[Bandolier]

Don't jailbreak

 

[fuzion11]

Don't jailbreak

gayest response of all time!

 

[Applejuiced]

Don't jailbreak

Why do people suggest things that are completely opposite what the requester asked for?

 

[tuna]

I tried it on other computers and the third one worked.

 

[CZK]

edit:Misread