First of all, welcome to LQ forums.
Your error is this:
99 invalid second stage index sector (LILO)
Errors 99 and 9A usually mean the map file (-m or
map=) is not readable, likely because LILO was not re-run after some sys-
tem change, or there is a geometry mis-match between what LILO used (lilo
-v3 to display) and what is actually being used by the BIOS (one of the
lilo diagnostic disks, available in the source distribution, may be
needed to diagnose this problem).
So you need to reinstall lilo.
1. boot from slackware CD, choose the kernel and wait till you hit the prompt (the one you typed setup when you were installing slack)
2. type
(thats a low L not an 1) to find out the the partition you installed slack (lets say hda3 for example)
3. make a new directory :
4.mount your slackware partition under this:
Code:
mount /dev/hda3 slack
5. use chroot:
6. reinstall lilo:
7. type exit
8.reboot (ALT+CTRL+DEL)