I can't access the Mac App Store, iTunes, or Software Update on Lion I updated from Snow Leopard 10.6.8 to Lion. The OS update process was all right.

I can access the Internet by Firefox, but Safari.
I think my network is all right.

So, I can access the internet from Lion, but I can’t use the Mac App Store, the iTunes Store or update my system. 

How can I fix these problems?
Are you running an actual Mac or are you running a Hackintosh?

This is a known Hackintosh issue
http://tonymacx86.com/viewtopic.php?f=135&amp;t=23153&amp;start=120