Switching fs-type from reiserfs to ext2/3

[Hermann-Josef Beckers]

I'm trying to switch a partition from reiserfs to ext2 or ext3. Both fdisk 
and diskdrake do as I tell them to do (get no errors, rebooted as told). But 
whenever I try to mount the partition, all I get is 

"Wrong filesystem-type, invalid options oder superblock of /dev/hdc6 is 
defect ..."

NOw I can't even switch back to reiserfs. System ist MDK8.2, Kernel 2.4.18.

Yours
hjb