I have a lyksys 54g my laptop works fine but tried hooking up a PC and sometimes it works great oyher times it says can not renew ip where do I start to fix it I'm lost

Intermittent problems other than being too far way, i.e. distance problems, is troubleshooted in a serial way, either from the router to the PC or the PC back to the router. This is what your router's (usually free) tech support or ISP would do for you over the phone.

I find when your situation happens is when you enter a non-standard but mathamatically correct local IP/Subnet mask combination when setting up your local network. Other than that, upgrade the router if possible or try a different router if it's not in the settings to verify it is the router as the problem and not an intermittant nic card problem. You can also try another PC - such as your laptop wired to the router to make sure of this.

On the PC side you can rebuilt your TCP/IP Stack by uninstalling all the components to your nic card, or the nic card itself and reboot and let the system reconfigure itself correctly.

Also check your ethernet wire is not at fault by trying a different wire. That is always cause for a fustrated surprise.