can’t defrag 98

I’m running win 98 2nd on a p500, 320 mb ram, 20gig hd on a ata 66 controller card. I have only a few trs running. my config.sys reads
Device=c:\windows\himem.sys
Device=c:\windows\emm386.exe noems
Device=c:\cdrom\oakcdrom\oakcdrom.sys /d:bunn
dos=umb, high
buffers=15,4
files=49
When I try to defrag or check for errors, the sys tells me that I don’t have enough memory. My largest exe size when at the c:\=562k (mem /c/p) My virtual memory is managed by 98. This machine runs games very well (quake). I wondering why I can’t defrag or check errors. I can’t imagion that I’m using all my system’s memory or resoures.