I was troubleshooting a SonicWALL Global VPN Client problem today. When viewing the log it kept saying "The peer is not responding to phase 1 ISAKMP requests". I found the following SonicWALL tech note and verified that all of the settings were correct. I then had a co-worker try connecting from our office with his client (since I didn't have it installed) and he was able to connect.
At this point I decided to reinstall the client, councidentially a new version of the client was released today so I downloaded and installed that one rather than the version that was previously being used. After installing the application launched and the Windows Firewall asked if I wanted to unblock it which I said yes to and proceeded to configure the client and was able to connect successfully.
So basically if I had added the Windows Firewall exception before uninstalling or disabled it all together the VPN client probably would have worked. Just wanted to post this incase you run into the same problem to check the Windows Firewall.