After uninstalling Vista SP1 you may get the yellow triangle error for
the wan miniport (SSTP). You can’t uninstall wan miniport (SSTP) or
delete it.

This is the solution:
Use the following commands to be carried out as the user Administrator
(Run as Administrator) from Command prompt (cmd):
netcfg -e -u ms_sstpminiport

You may have to find the course Hardware ID device from the Device
Manager and selecting the Details tab-> Hardware IDs if it is not
‘ms_sstpminiport’ which is causing the problem.

Taken from: Here