Scandisk/Defrag problem

I have multiple PC’s 650mhz – 900mhz, Win98SE, 256meg Ram, 19 gig hard drives, all pIII’s. I cannot run either scandisk or defrag in Windows, (DOS works fine), I get an error message that the system does not have enough memory to run the program (obviously incorrect). I have seen posts at a couple of sites about a download from MS to fix this problem, but I can’t find the posts nor can I find the download at microsoft.com. Does anybody know where this patch is????