To me it seems like Slackware picked a partition from your Windows 7 HDD (notice the "ntfs filesystem") and tried to use it as its root (/) partition.
Obviously, that's gonna fail epically...
This is probably due to the fact that both in your /etc/lilo.conf and /etc/fstab files you specified the partitions by device name (e.g: /dev/sda4). When you plug a new disk on your PC motherboard, those device names are (almost certainly) gonna change, shifting by a letter. For example, if your Slackware disk previously was /dev/sda, now it can be /dev/sdb, and /dev/sda points to the Windows 7 disk.
If your intention is to boot the Slackware partition without having to care whether or not the Windows 7 disk is plugged, I think you should modify your /etc/lilo.conf and /etc/fstab files to only use the disk UUIDs instead of the device names. The UUID is a sequence of characters which uniquely identifies a disk/partition. You can view the UUIDs of your partitions with
You should modify the /etc/fstab entries from (this is an example picked from my fstab file):
where xxxxx is the UUID for the /dev/sdb10 partition as /dev/disk/by-uuid/ reports.
/etc/lilo.conf "root=" entries should be modified from this
Please pay attention to the boot= option in /etc/lilo.conf. That option is not compatible with device UUIDs, so you should carefully change it whenever you need to reinstall LILO in the correct hard disk MBR.
To apply these changes you have 2 ways. The simpler one consists of temporarily disconnecting the Windows 7 disk from the motherboad, boot Slackware as usual (it should boot with no problem now) and perform the changes (edit /etc/fstab,/etc/lilo.conf and reinstall LILO).
The not-so-simply-one consists of booting the system from the Slackware install disk, mount the Slackware root partition under a temporary folder and chroot in it. In order to see the UUIDs of your partition, you have to mount the /proc pseudo-filesystem prior