AppStore - "Your device or computer could not be verified."

[fubar072]

Try this:
1 Turn off firewall

2 Delete NetworkInterfaces.plist in Library/Preferences/SystemConfiguration

3 Create new network location

4 reboot

5 try to log into App store

6 turn on firewall

i found this while searching for a solution to the problem. found it in an apple discussion forum.

This worked for me too, thanks a lot