It seems that you have two OSs installed on the HDD and my guess is that W2K made a partition for itself and Win98 is sitting in its own partition of 5891MB. Perhaps you were upgrading W98? or trying a dual boot installation?
If Win98 was present when installing the W2K or XP files, the install process places the bootloader files needed for NT-OS in the Win98 main drive (usually C:) and the files can get corrupted or lost. OR if Win98 was installed later it eliminates the files that NT needs to start.
This problem can be complicated to solve and a clean install would be best. If W2K is what you want, boot up from the CD or Floppies. After loading the setup files you will be asked to select a partition. At this point delete all the partitions and other OSs one by one. Then make the partition (4 or 5 GB is plenty for OS and programs), make a couple more partitions for Pagefile (prev Swapfile) and for storing your date then install the NT system.
If later you want to install Win98 as well, use a third party partitioning software (Partition Magic or System Commander). In general, separate partitions is less complicated than dual booting because if Win98 dies on you in a dual boot scenario, you could lose the loader files for the other OS or if you need to re-install W98 you will lose the loader files for NT.
Hope this helps.
