AVG's website has these tools: 


-AVG Repair NDIS<http://aa-download.avg.com/filedir/util/AVG_Repair_NDIS.exe

-If you are using AVG 2013 on Windows XP, the AVG Firewall may stop working 
after recent program update. The firewall then shows status Stopped. When 
you click on Firewall, it reports the following status: 
Firewall cannot start, because an error has occured in communication with a 
driver. Please contact AVG Technical Support.


Do you have AVG PC - Tune Up?  If so open it and look in "Disabled Programs" for Bonjour and/or FingerPrint.  It may have decided to disable either Presto or Bonjour for you.  If this is the case re-enable.


-AVG has to create the "Bonjour allow rule" as part of the Presto install.  If Bonjour is already permitted, AVG does not recognize it as part of Presto.

-Go into the AVG Firewall rules and delete the Bonjour service rule.  Close Presto and re-install it.  When you do AVG creates a new firewall rule and allows Bonjour.  The printers from the desktop computer should appear in the AirPrint window on the iPad.

- http://forums.avg.com/us-en/avg-forums?sec=thread&act=show&id=190921

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