Problems with Internet Explorer 7 opening default Telnet client
By default, NETLAB+ will open the built-in console viewer or remote PC viewer. These viewers are Java based, so there is no special client to load (other than Java). You may also use your own Telnet software for Remote Console connections.
If a third party (local) Telnet client is configured in your NETLAB+ profile, the local Telnet application will open and ask the user to log in with the NETLAB+ user ID and password.
Problem:
In Internet Explorer 7 and later, the Telnet protocol handler is disabled by default. (See FEATURE_DISABLE_TELNET_PROTOCOL feature control). As a result, you will not be able to establish a remote console connection to a lab device, using your third party (local) Telnet client through Internet Explorer 7.
Solution:
Before reading the solution outlined on this page, you should recognize that NDG is not responsible for any damage caused to your registry or operating system by changes that you perform to your computer. This example is meant to outline steps that can be taken if you choose to edit your registry in order to use your preferred Telnet client. NDG has successfully used this change to utilize IE 7.0 for the purpose of setting a preferred Telnet client for use with NETLAB+. NDG will not assume responsibility for any change you make to your PC operating system.
Add the following key to your registry:
"iexplore.exe"=dword:00000000
- Run regedit from the Start menu
- Locate the FeatureControl directory
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Main\FeatureControl\FEATURE_DISABLE_TELNET_PROTOCOL] 
- Add a new key into the FeatureControl directory
- Name the new key "FEATURE_DISABLE_TELNET_PROTOCOL"
- Add a new DWORD value
- DWORD name should be "iexplore.exe" and value 0
