Mouse sluggish during heavy disk activity

Yet another problem under ME -- the mouse becomes very sluggish when there's a lot of disk activity. I have two drives on different IDE channels, get the same problem with both of them. The mouse is connected directly to the PS/2 port and uses IRQ12. The system is a multi-OS and I do not have this problem under W2K. I do have the problem under Linux, but only if I do not switch on the DMA mode for the disk drivers -- after I do that, the mouse is fine under Linux. I thought maybe I needed to turn on DMA mode for ME, but I can't figure out how to do that. Also I should mention that this was not a problem on my old (Intel-based) system where I had the same software and the same peripherals. Downloaded the VIA 4in1 drivers but under ME the ATAPI driver is not installed (also tried under W2K, it installs there but I don't seem to get any control panel for setting the DMA modes). Help!