The following is a Copy / Paste from a posting I have made on the Windows MS Forum which involves Norton 360:
Thanks for your reply. I seem to have identified the source of the problem. However, the solution is only a temporary one so you may be able to help me with finding the long-term solution.
When I get 'purchase cannot be completed' and 'app cannot be installed' messages it is because the Windows Firewall has been turned off ---- if I turn it on again (restoring the default settings) current problems with the Store go away. But a little while later they re-appear and I find that the Windows Firewall has been turned off again. This is presumably because Windows Firewall is being turned off automatically by my Norton 360 Anti-virus software to prevent the two Firewalls from clashing. I remember when I installed it there was a statement that Windows Defender needed to be disabled.
Can you give me advice on what to do to resolve this permanently? I can also ask for advice from the Norton community Forum, to which I subscribe.
What also puzzles me is why this issue has suddenly appeared, after using the W8.1 Tablet with Norton for several months without having Firewall difficulties.
I look forward to your response.
Clayto