User reports began to spread on the Internet who encountered a blank device manager and network connections after upgrading their Windows XP system to Service Pack 3. The problem was largely attributed to software that was monitoring the Registry for changes, many Symantec customers had problems with a feature called SymProtect that would cause the post-installation problems.

Symantec issued a patch on June 5th and Microsoft released a patch as well a few days ago that should solve the issue for users who are experiencing blank device managers and are missing networks in the network connections menu.

Users now have the choice to use the Microsoft patch or the Symantec fix to correct the issue. Using the Symantec fix however makes only sense if a Symantec product was installed on the system during the upgrade to Windows XP Service Pack 3.

Source: ghacks