Partition error with dual boot Arch/Ubuntu Linux

Question

I have Ubuntu installed on an ext4 partition and Arch installed on some other logical partiotions in an extended partition. There is no problem when I only use one system of both, but when I use them alternatedly the following happends:

• Case A: Use Ubuntu first, then start Arch: On booting Arch, boot fails at some point and the system says there is something wrong with the home partition. This can be easily fixed with fsck.
• Case B: Use Arch first, then start Ubuntu: On booting, Ubuntu displays something with hard drive checks, maybe it takes a little longer to boot, but then starts normally.

Why is this happening? How to fix it?

EDIT 1

• This shows the partitioning in GParted:

  

/etc/fstab of Ubuntu:

# /etc/fstab: static file system information.
#
# Use 'blkid -o value -s UUID' to print the universally unique identifier
# for a device; this may be used with UUID= as a more robust way to name
# devices that works even if disks are added and removed. See fstab(5).
#
# <file system> <mount point>   <type>  <options>       <dump>  <pass>
proc            /proc           proc    nodev,noexec,nosuid 0       0
# / was on /dev/sda8 during installation
UUID=bbd528b3-5e5e-4b33-aabd-b386c43b7347 /               ext4    errors=remount-ro 0       1
# swap was on /dev/sda9 during installation
#UUID=4329a4c7-2ee3-43a6-b353-f83e24047122 none            swap    sw              0       0
/dev/fd0        /media/floppy0  auto    rw,user,noauto,exec,utf8 0       0
/dev/mapper/cryptswap1 none swap sw 0 0

# Dateien: /dev/sda3: LABEL="Dateien" UUID="71B500522BEFD2C2" TYPE="ntfs"
# diabled becuase it mounts itselfs again: /dev/sda3 /media/sda3 ntfs auto 0 0

UUID=71B500522BEFD2C2 /media/Dateien ntfs defaults,nls=utf8,uid=1000,umask=000,windows_names 0 0

• Arch is sda[6-9]
• Ubuntu is sda2

EDIT 2

/etc/fstab of Arch:

# 
# /etc/fstab: static file system information
#
# <file system> <dir>   <type>  <options>   <dump>  <pass>
tmpfs       /tmp    tmpfs   nodev,nosuid    0   0
#/dev/sda5 swap swap defaults 0 0
#LABEL=/ / ext3 defaults 0 1
#LABEL=/boot /boot ext2 defaults 0 1
#LABEL=/home /home ext3 defaults 0 1
#LABEL=/opt /opt ext3 defaults 0 1


#/dev/sda5 swap swap defaults 0 0
UUID=0d4af9ca-1654-4153-9367-d547fdf95fb9 swap swap defaults 0 0

#LABEL=/ / ext3 defaults 0 1
UUID=551c8fda-808b-4292-9549-a7b001f11b52 / ext3 defaults 0 1

#LABEL=/boot /boot ext2 defaults 0 1
UUID=d56c00ec-3373-40c8-ba79-b871a778c60a /boot ext2 defaults 0 1

#LABEL=/home /home ext3 defaults 0 1
UUID=d9b0fc01-8a85-48ed-86e6-25a1ef1f2521 /home ext3 defaults 0 1  

#LABEL=/opt /opt ext3 defaults 0 1
UUID=0ef3c4db-9026-4081-a84a-db12c7a5b5bf /opt ext3 defaults 0 1