If you have a laptop with Windows 98 installed and a DVD player, upgrading the OS to Windows 2000 will result in the DVD playing a movie with dropout and sputtering sound. This is caused by the DVD player I/O not being DMA enabled.
In Windows 2000, enter the Device Manager and select IDE ATA/ATAPI controllers. The DVD/CD is usually installed in the Secondary IDE Channel. Select it and check the properties. Set both Device 0 and Device 1 Transfer Mode to "DMA if Available" under Advanced Settings tab.