DMA is turned off on my HDD

[Anton Liaukevich <anthonyl@uvaga.by>]

In the beginning of July I reinstall my Debian system (lenny). At once I 
discover that loading cache in Aptitude (ncurses-UI mode) is very slow 
and in general my system is very slow.

In several days I discovered that DMA is turned off on my HDD (fsck 
sayed it while Debian booting). Please, help me turn on DMA mode.

My hardware:
    motherboard: Epox 8RDA3I rev 3.3 (nForce 2 Ultra)
    hdd: WD1200JB (ide, 120gb)
    cpu: Sempron 2200 (k7)

My software:
    Debian lenny
    kernel: linux 2.6.24-1-686
    bootloader: grub 0.97-41

My Linux partitions:
    hda3: / ReiserFS
    hda4: /usr/local/ Ext3
    hda7: swap
    hda8: /home/ EXt3

I had scanned my hdd with native WD scanner and hadn't detected any 
error. Memory scan (memtest86+) also hadn't detected any error. 
Moreover, Windows XP on another partition of this hdd working normally 
and HDD Health program on it (for S.M.A.R.T viewing) don't predict 
T.E.C. in the near future. Also after previous installation of Debian 
lenny my hdd was working fast.