This dialog is posted on Pro Tools version 7.3 systems on Windows XP with no network interface, or if a network interface (e.g. a wireless adaptor) is disabled. It does not appear to be linked to any other problem in Pro Tools, so you should be able to safely ignore this error and click OK to dismiss it.
This is fixed in version 7.3.1 which can be found in the Downloads section for the specific type and platform of Pro Tools software on the Support & Downloads page.
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