Q: Upgraded to OS X lion and now I cannot connect to the Internet.  Wifi or hard wired. Any ideas?

Restart your modem and routers and reset your SMC on your mac.

This might help

http://support.apple.com/kb/TS3802

Launch Terminal app. and try to ping your router IP address.

so type:

ping -c5 x.x.x.x

(where x.x.x.x is your router IP address like 192.168.1.1 )

Launch another Terminal window and type:
ping -c5 www.google.com

If ping's to your router work while ping's to google fail, the issue is with your router, not the client. You can paste the output here if you need help.

how do you know if you are running avast?

I'm having the same issue. What I was able to come up with is wired & wireless, DHCP does not give me an ip address. So I set one manualy and was able to get a little further. I was able to ping my router, and Google by IP address. Pinging Google by name does not resolve. So for some reason i'm getting DHCP issues and DNS issues but every other device in my house runs great and the Macbook worked before I installed Lion.  As far as I know, I do not run avast. I'm completly lost at the moment on what to try next.

Try disabling AVAST if you have it installed. I had same issue and screwed with it all day! Finally found this solution here on a different forum and it worked! Good luck

Don't have AVAST installed Never have.

Bummer! Maybe try disabling other virus scanners if you have them installed. Sorry I could help :-(

Oops and I meant to say I found the solution on this forum in my post above! Thank you guys all for helping me!!!

No other virus scanners.

Bummer! Try calling apple they had me do a bunch of things today that might work for you. Good luck and sorry I couldn't help!

Thank you for trying at least.

Necrite,

Does your Mac get a DHCP IP Address ? if it does, you can set the DNS manually. Use something like 8.8.8.8 and 8.8.4.4 (http://code.google.com/speed/public-dns/)

But if your client never get's an IP address try this:
On the Mac, launch Terminal and enter:
sudo tcpdump -i en1 -s0 -vv -p port bootps

*assuming en1 is your wireless adapter.

Now turn WIFi Off and On, and give it a few seconds for the issue to reproduce. Copy paste the output of the Terminal here and I can help you. What we are trying to do is search if the Mac trie's to get a DHCP IP.

Also make sure your DHCP Server (wireless router) gives out enough DHCP leases.