dma problems

my stepfather just purchased an amdk6-2,500mhz chipset with a Tyan S1590s Trinity AT100 motherboard slapped it together with a creative labs cd rom and a samsung hard drive. Did an upgrade install from win95 to win98.He now has a problem with the dma,where as it is non-functional (cd-rom and hard drive now slow up the pc.)He did mention having to work around a cab file, but im not certain that it had any baring on the dma.