I have a connectivity problem that has been a minor nuisance recently, and wondered if anyone could point me in the right direction before I start to try and find that direction myself. I've tried Google'ing and looking around but haven't been able to find anything.
I'm using Windows 8 Pro, and when occasionally when the system has been up for at least a couple of days (though in some cases it may have been shorter than that) I lose Internet connectivity, except that I can still access any sites I've visited before this i.e. I have Twitter open in an app tab in Firefox, so I can still browse twitter.com. I try to access the router control panel but I get a 400 Bad Request error. When I try to go to any website I haven't visited during that session, I get a "Connection reset" error in Firefox - other browsers return errors as well. A system restart sorts things out. The fact that I can still browse sites I've previously visited during the current session makes me think it is possibly a DNS issue, so I've changed my DNS servers from my ISP's (Sky) to Google, still waiting to see if it has made a difference.
I'm using Comodo Firewall and Avast Antivirus.
Grateful for any help.