Do you have any Install Discs for this Mac?
What happens if you hold the Option/alt key down at bootup?
Does it boot to Single User Mode, CMD+s keys at bootup, if so try...
Repeat until it shows no errors fixed.
(Space between fsck AND -fy important).
Resolve startup issues and perform disk maintenance with Disk Utility and fsck...
Not knowing which Sawtooth you have makes this a bit harder to reply on. If you look at this link, the Sawtooth series of macs came with OS9:
While it is possible to run OSX on these machines, it does take a bit of work. It has been a few years since I sold my last Sawtooth, so I had to do a bit of google searching:
http://resale.headgap.com/osxnotesG4.html (This will at the very least get you started)
From what I remember on my G4/400 Sawtooth, maxed at 2 gigs of ram, 10.3.9 was SLOW to say the least. I didn't even attempt 10.4 with the issues of loading 9.2 first, bootstrap and what not, it was truly not worth the effort. Depending on what you want to do with this macs. Getting your hands on a copy of 9.2.2 or going the ljnux route might be the best option.
I have had some good experiences with MintPPC on a few of my rigs here, I have been pleasently suprised that with the simple switch of an OS, you can achieve so much more.
Hope it helps
If you don't know the model, find the Serial# & use it on one of these sites, but don't post the Serial# here...
How to find the serial number of your Apple hardware product...
BTW, I can run 10.5.8 on a 450 Mhz G4 with... let's say acceptable results, not great though.