On Windows xp it is common for the Cisco VPN client to sit on the task bar and not maximise (and show as disconnected). Here is a solution.
- Start VPN Client
- Start Task Manager
- Select VPN client from Applications tab, right click on it and click Maximize
- VPN client will be visible in maximized form
- Go to Options -> Preferences -> Save Windows Settings. Uncheck this.
- Go to Options -> Simple Mode.
- Go to Options -> Advanced Mode.
- Now restart VPN client.