Thank you for your message. You mentioned you are using the model wrt54g. Could you please let us know of the revision number of your router? You can find this information at the sticker at the back of your router.
Please perform the following steps: Disconnect your router from your computer. Reboot your router. After the router reboot please reboot your computer too. Connect to your router wirelessly to check if you are getting a hotspot splash page. Let us know how it goes.