Is your partition FAT16 or FAT32?
What's the size of your partition?

FAT32 28 gigs

See http://support.microsoft.com/kb/184006/en-us . especially this
sector:

quote
The ScanDisk tool included with Microsoft Windows 95 and Microsoft
Windows 98 is a 16-bit program. Such programs have a single memory
block maximum allocation size of 16 MB less 64 KB. Therefore, The
Windows 95 or Windows 98 ScanDisk tool cannot process volumes using
the FAT32 file system that have a FAT larger than 16 MB less 64 KB in
size. A FAT entry on a volume using the FAT32 file system uses 4
bytes, so ScanDisk cannot process the FAT on a volume using the FAT32
file system that defines more than 4,177,920 clusters (including the
two reserved clusters). Including the FATs themselves, this works out,
at the maximum of 32 KB per cluster, to a volume size of 127.53
gigabytes (GB).
unquote

DOS is a 16bit programm, so other plain DOS tools and DOS itself might
have the same limitation.

--
herzliche Grüße,

Klaus Meinhard