First contact your ISP. You need to confirm that the issue is not on their end.
Change your router channel. Sometimes this is all you will have to do.
Power cycling the router. Read the router's user manual or contact their tech support for instructions.
System Preferences/Internet & Network/Network
Unlock the padlock
Click the Assist Me button
In the popup window click the Diagnostic button.
System Preferences/Network- Unlock padlock. Highlight Airport. Network Name-select your name. Click on the Advanced button. Airport/Preferred Networks-delete all that is not your network.
Place a check mark next to "Remember networks this computer has joined." Click the OK button and lock the padlock. Restart your computer.
http://support.apple.com/kb/TS1920 Mac OS: How to release and renew a DHCP lease
No internet connection (wireless)
Check to see if an extra entry is present in the DNS Tab for your wireless connection (System Preferences/Network/Airport/Advanced/DNS).
Delete all extra entries that you find.
Place a check mark next to "Remember networks this computer has joined."
Other resources to check into:
I have been told that it is a Safari thing.
I do not use Safari. Post in the Safari forums to see if the users there are experiencing the same issue as yourself.
Disconnect all peripherals from your computer.
Boot from your install disc & run Repair Disk from the utility menu. To use the Install Mac OS X disc, insert the disc, and restart your computer while holding down the C key as it starts up.
Select your language.
Once on the desktop, select Utility in the menu bar.
Select Disk Utility.
Select the disk or volume in the list of disks and volumes, and then click First Aid.
Click Repair Disk.
Restart your computer when done.
Repair permissions after you reach the desktop-http://support.apple.com/kb/HT2963, empty the trash and restart your computer. A new plist file will be recreated after you use System Preference again. Post back to let me know if the padlock remains locked.
Also when I lock the lock it will not let me apply.
It's not suppose to! That's the purpose of the padlock once it's locked.