I would bet there is still something there related to the virus. A backup of your data to something external and a reformat is the easy answer. Virus's are very hard to remove and you can never be sure your system is completely free. This would also help you to determine if it is a hardware problem. If you reinstall and it is still going on, then worry about the hardware. It could also be corrupted drivers, try uninstalling and reinstalling your network drivers.