Places to look for troubleshooting information
The knowledge base is pretty useless.
Go to the hardware documentation, and select the Network Connect and W-SAM Error Messages
document for your IVE version.
If that doesn't help, you can run the NC Troubleshooting
application (in the appropriate program group) which will dump the activity of your network connect session while it is happening; usually there will be a clue in there that will help.