Your going to have to edit the registry in order to fix this. Here's the help information from PTC
Solution Details - TPI 103538
Created Date 07-Jul-2000
Last Updated 29-Dec-2009
Title
When Not Connected to a Network, Windows Machines May Return "HostID" Errors ( -96, -15, -9) for Pro/ ENGINEER and the FLEXnet License Server Due to the Windows Media Sensing Feature.
Description
When disconnected from a network Windows machines may disable certain network cards resulting in licensing errors from Pro/ENGINEER and the PTC License Server.
Pro/ENGINEER may return
error: "(-96) License server host is down or not responding" or error: "(-15) Cannot connect to license server system" if configured to a license server
or
error: "License request failed for feature PROE_Foundation: -9: Invalid host." if configured to a locked license.
FLEXnet License Server error log may contain messages similar to the following:
Error: Wrong hostid on SERVER line for license file: <flexnet loadpoint=">\licensing\license.dat
SERVER line says PTC_HOSTID=00-11-22-AA-BB-CC, hostid is PTC_HOSTID=00-AA-11-BB-22-CC
Resolution
This issue is related to the 'media sensing' feature of Windows 2000 and later (including XP and Vista) and disabling this 'media sensing' feature will resolve the issue.
For more information on 'media sensing' see
2. Locate the following registry subkey: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Tcpip\...