Hi to anyone who has the same poblem as i did here is the setup i finally used to get this working
Sonic firewall was TZ170 running standard OS 3.1.0.15
Sonicwall settings
use DH Group2
Main Mode and not agresive
set sa lifetime to 86400 (this is the max cisco IOS supports)
Phase 1 set hash to sha1 and encrption to 3des
phase 2 set protocol ESP
Encryption 3des
authentication sha1
tick the keepalives box and enable "try to bring up all possible tunnells"
Settings i used on the cisco router
crypto isakmp policy 10
encr 3des
authentication pre-share
group 2
crypto ipsec transform-set myset esp-3des esp-sha-hmac
crypto map mymap 10 ipsec-isakmp
set peer 1.1.1.1
set security-association lifetime seconds 86400
set transform-set myset
This set up worked instantly so my be worth making a note of.
hope it helps someone.
regards
colin