Q: iMac connect to wi-fi but no internet but my other devices work fine

what all do you have on your desktop? A cluttered desktop from downloads not deleted after installing can mess up things at times.

How often do you empty the cache, and reset safari?

Did you do the PRAM and SMC thing? I will find where those are explained- I just read it here on these discussions moments ago..

http://support.apple.com/kb/HT3964 for reset the SMC

and the PRAM thing:

http://support.apple.com/kb/ht1379?viewlocale=it_it

This has worked for a few...

Make a New Location, Using network locations in Mac OS X ...

http://support.apple.com/kb/HT2712

10.5.x/10.6.x/10.7.x instructions...

System Preferences>Network, top of window>Locations>Edit Locations, little plus icon, give it a name.

System Preferences>Network, click on the little gear at the bottom next to the + & - icons, (unlock lock first if locked), choose Set Service Order.

The interface that connects to the Internet should be dragged to the top of the list.

Instead of joining your Network from the list, click the WiFi icon at the top, and click join other network. Fill in everything as needed.

Also, turn off IPv6:

System Preferences » Network » AirPort » TCP/IP tab » Configure IPv6

Or whatever interface you connect with.

For 10.5/10.6, System Preferences>Network, unlock the lock if need be, highlight the Interface you use to connect to Internet, click on the advanced button, click on the DNS tab, click on the little plus icon, then add these numbers...

208.67.222.222

208.67.220.220

Click OK.

DNS Servers are a bit like Phone books where you look up a name and it gives you the phone number, in our case, you put in apple.com and it comes back with 17.149.160.49 behind the scenes.

I am the original poster but I cannot seem to log in using my old id. Anyway, nothing works so far I have tried. After I reset or create new location, it works for several seconds and went dead.

Could be virus or malware?

Oh, when I am able to get on for briefs moment, it will ask for my password to Facebook, hotmail, gmail. Every time I click ok, it will keep on asking me password!!!!!

Hello...I cannot say anything about the malware/virus question... BUT, I wonder if something got screwy with your Keychain. So I clicked on the Help in the menu at top of the screen, while I had system preferences open... There is a lot there to read.. I am in 10.7.4, so it may not exactly match what your machine says (do that search too, for precision).. but one thing that I think MIGHT be associated with your dilemma could be the following (did you set new passwords before when you did as BDAqua advised? That will do things...) the window I found:

1. Open Keychain Access, located in the Utilities folder in Launchpad.

   Open Keychain Access

2. If you don’t see keychains in the left column, choose View > Show Keychains.
3. Select a keychain, from the Keychains list. The application’s keychain would probably be in your login keychain.
4. Double-click the password in the Keychain window, and then click Access Control.

   • To allow all applications access to this password, select “Allow all applications to access this item.”

   • To control access to this password, select “Confirm before allowing access.”

   • To require the keychain password instead of the application password, select “Ask for Keychain password.”

   • To add individual applications that can access this password, click Add (+), and then navigate to the application you want to add.

5. Click Save Changes.

Now my wife iMac also having same issue. Only android phone, iPad and pc laptop can access Internet only. Both iMac leopard and lion went dead!

Tkx Crampy, i had the same problem

What i did was connecting to another wifi network. then it asked for a keychain password.

after switching back to my preffered network everything worked fine again.