Ok 1 st from console do a
"crypto key generate rsa modulus 512"
to generate the rsa keys, afterwards do a wr mem and try to ssh the inside IP address.
Also activate logging on the PIX and look at the logs for more information should the key generation won't work.
2 nd don't use generic statements like 0.0.0.0/0 use the network where you are incoming from if you are being nated on the way to the inside interface the logging should warn you that someone from IP xxx.xxx.xxx.xxx attempted to ssh the machine.
let me know if it helped
Best Regards
