Display problem

Have you checked the Device Manager for conflicts/correct driver?

It does sound like a driver problem...windows may have only installed a standard pci driver for the display. Even if the correct driver is installed I'd still reinstall it.

go into Safe Mode (keep pressing F5 during startup) go into The Control Panel>System>Device Manager. Click the plus beside the Display Adapter and highlight the device that comes up directly underneath, then Click Remove.
Restart the computer and allow Windows to detect the hardware....make sure that its detected the S3 Savage and not the Standard PCI display adapter. (If it has you'll have to manually type in the path to the driver).

If you've already done this go into the device manager and double click on the device to bring up the properties window. In the general tab make sure that "Exists in all hardware profiles" is checked. If everything looks ok there click on the resources tab to see if windows has reported any conflicts.

If the Display properties allows you to select a different setting (eg. 1024x768) then this indicates the correct driver is installed...you could try an older driver if there is one listed in the website.

Was there any new software added to the computer at the same time the problem occured? If so check your startup group items to see if the software is there and remove it.

it's a driver issue.
reinstall the driver from your original disk with came with the videocard. For a newer version of the driver look at another site, (I went to the site, and I am not so sure about it) you can install dx8 as a alternative).
Also check make sure your monitor is set as the NEC and not as a standard vga.

Leopold

after you selected your new settings have you hit the apply button then the okay button..doesn't sound like a driver issue since all was working ok until you changed your disp settings.
good luck

Is the driver you've downloaded, the correct driver for you card? I used to have the same problem with different driver.

If yes, try to install a known working driver from other company, restart your PC, change it back to the S3 savage driver, and click 'Apply'. Restart again.

Hope it helps.