No internet via ActivSync on Windows Mobile

Well, a new MSN bug. If you install ActivSync 4.2 on your computer your mobile device no longer can access internet via ActivSync connection. You end up with:
“The page you are looking for cannot be found due to unknown error 0x80072f78” in internet explorer on your mobile device.

ActiveSync version 4.2 made a change to how it interacts with the Windows networking stack to use Layered Service Providers (LSPs) on outgoing Desktop-Pass-Through connections.  This allows for improved compatibility & policy compliance in environments where connections to the internet must be passed through these LSPs (ISA Proxy is one such example).  

Unfortunately, it appears this change has caused some issues for a small segment of users who have LSPs that interfere with ActiveSync communication.

There is a registry key which can be created to essentially remove this change & revert to ActiveSync 4.1 behaviour.  This key is:
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows CE Services]
“AllowLSP”=dword:0