can't mount any secondary drive partitions

[admin at homemachine.net (Tom)]

Hi,

I have just installed centos 4.2 on machine remotely and everything went 
well, a second drive was installed, I partitioned it, rebooted and then 
tried to mount it but keep getting the error

mount: /dev/hde6 already mounted or /mnt/1 busy

this happens with every partition on any secondary disk, we put a third 
disk in and get the same error.

I have googled but not found anything relevant, most info relates to LVM 
or raid of which we have neither.

any help greatly appreciated.

tom