You are doing a restore to the same OS 3.0, essentially refreshing the firmware on the device, it's possible it did not load properly the first time.
Make sure to sync and backup the phone first.
Use the following steps to restore your iPhone:
Taken from Apple Support online
- Make sure you have the latest version of iTunes installed and running before attempting to update.
- Connect your iPhone or iPod touch to your computer.
- Select your iPhone or iPod touch when it appears in iTunes under Devices.
- Select the Summary tab.
- Select the Restore option.
- When prompted to back up your iPhone or iPod touch's settings before restoring, select the Back Up option (as seen in the image below). If have just backed up the device, it is not necessary to create another.
In terms of the messages to update, you can always ignore them...Apple isn't forcing you to do updates.