De uma pesquisa rápida,
The sp3 install might have reset your power management settings so it goes into standby at 15 minutes (this is default on a lot of HPs). A quick google search shows that some people are having problems with sp3 and power management. If it goes into standby it will drop the network connection to save power. Set it to never go into standby or hibernate.
Tente alterar as configurações de gerenciamento de energia.