Error mounting fat partition

[Stefan Malte Schumacher]

Hi

I already posted this problem once and I have tried to solve this on my own
but I wasnt successfull. I have added my Fat and Fat32-Partitions to my
fstab and two of the four get mounted without any problems. But when I try
to mount the primary partitions on my first and third drive I get the
following error messages :

root at avalon /mnt mount -t msdos /dev/ad4s1 I
msdosfs: /dev/ad4s1: Invalid argument

root at avalon /mnt mount -t msdos /dev/ad0s1 C
msdosfs: /dev/ad0s1: Invalid argument

Messages of these kind appear in /var/log/messages. I have checked the
filesystem from Win2k and they are okay. 

Sep  4 15:55:10 avalon kernel: Next free cluster in FSInfo
(4294967295) exceeds maxcluster (1034161)

Strangely I was until recently able to mount /dev/ad4s1/, it seems it just
stopped working yesterday - and I did neither change the filesystem nor my
kernel or anything. 

Please enlighten me what is wrong. 

Bye
Stefan