Currently Being ModeratedDec 5, 2012 10:01 PM (in response to ffmusik)
I'm guessing it just says "Cannot Connect to the App Store"
Can you tell me, do you have any anti-virus software running? Often they will cause this symptom, the same with firewall stuff.
If you don't have any of that, try this for now:
Network Preferences -> Advanced -> DNS > DNS Servers
Add these two entries:
They are Google DNS servers.
Remove everything else. Leave Domains as is.