Losing Internet Connectivity

Hi,

I am having an issue with my Windows 8.1 Desktop (win 8.1 Pro with Media Center 64 bit) in that it is losing the IP address several times a day, which stops any browser from working. I fix this by entering "netsh int ip reset resetlog.txt" at the cmd prompt & restarting, but this is only temporary. For the past couple of days this has been occurring at 9am and 9pm. but for the prior week or so it was 12am or 6am. I can't work out what is causing this. This behavior began on 2/2 but no updates were done on that date. In the event log I find 4 event corresponding to the times I mention:

Error Service Control Manager
The Base Filtering Engine service terminated unexpectedly. It has done this 3 time(s).

--------

Error Service Control Manager
The Diagnostic Policy Service service terminated unexpectedly. It has done this 3 time(s). The following corrective action will be taken in 120000 milliseconds: Restart the service.

--------

Error Service Control Manager
The Windows Firewall service terminated unexpectedly. It has done this 3 time(s).

--------

Error Service Control Manager
The Network Connected Devices Auto-Setup service terminated unexpectedly. It has done this 3 time(s).

---------


Can anyone offer advice on the cause and how to fix? I have done a full scan with Trend Micro but no virus or malware is detected.