Dell notebook hd partition problem/snafu

specs:
bot new in 2000
450 mhz
20 gig
win98 se
128 ram
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Here's the problem
I recently wanted to reformat and partition to clean up the junk on the HD

so I used Partition Magic to create D: a 6 gig partition. to save some data,
then I reformatted the C: drive, after all done I tried to install Zone Alarm
but got the error I don't have root certificate??? so I repeated after using fdisk, it showed 19.xx gig, but in win explorer it showed 12.9 gig.

then I used fdisk to delete all the partitions and active/extended etc.....

then I got the error message when rebooting from the Dell Win98 SE CD, something like unrecognized disk compression present

is there a utility to correct this, I couldnt find anything with Partition Magic, or I overlooked it??

TIA