I have two OS (Slackware Linux and Windows XP) and use Lilo to choose which to load.
Some days ago (in Windows) it showed continuosly a blue screen with written "there must be a problem with drives ..." and something like that. Any time I started Windows it appeared. So I restarted in Safe Mode and used Partition Magic to create a partition, but during this operation I changed the Linux partition to NTFS. The result was that after restarting it showed a sequence like:

L 99 99 99 99 99 99 99 99 99 ...

and it freezes!

The Linux Loader becomes mad because it doesn'0t find anymore the Linux partition. I have tried with the Slackware Linux CD but it doesn't solve the problem. Anyway I'm a beginner in Linux so I don't know how to fix the Linux Loader to work properly.

You changed the Linux partition to NTFS?? God save you!
I guess you will have to reinstall to use Linux.
And if you really want to save Windows only .. boot with CD and do liloconfig again. Thats all.

To do liloconfig.. run setup and select "Run installation scripts again".
You could also recover Windows using any windows recovery Cd you might have.

I tried installing Linux again, but Lilo still doesn't work.
Anyway, I don't need the Windows system. I want just to save some files, which I think I can save from Linux and then format the NTFS partition.

I have a NTFS partition in /dev/hda1 and I've installed Slackware Linux in /dev/hda3, but Lilo doesn't work. Even if during the installation of Lilo I choose to boot only Linux ...

I found the command dd if=/boot/boot.0300 of=/dev/hda bs=446 count=1 for uninstalling Lilo if it has been installed in /dev/hda. Does it work? I'm not sure that Lilo has been installed in /dev/hda. How can I found out where it has been installed?