That you can get in to OS 9 with extensions off indicates that you've got an extensions conflict, a very common OS 9 problem. To resolve, the best way is to usually restart in OS 9 with the space key held down, which should bring up Extensions Manager before booting. Using Extensions Manager at start up, you should have a pull down menu that is probably on something like "My Extensions" or something similarly named to indicate that you're using a set of extensions that includes extensions for things you've installed (as opposed to the stock OS 9 extensions). To troubleshoot, what you should do is turn half your extensions on and leave the other half off (always make note of where you've made your halfway dividing line), then let it finish booting. If it boots normal with the first half on, go to Extensions Manager and turn on half of the second half of extensions and then restart. If it continues to boot properly, use Extensions Manager to turn on half the remaining extensions and restart. Keep going along with this pattern of turning on half the remaining extensions and restarting until the computer no longer boots properly. Provided you've kept track of your cut-off points, you've pinpointed the batch the bad extension is in. Restart into Extensions Manager and disable half of the last batch you enabled (or, if you're just down to a few extensions, you can do them one by one, restarting each time). Keep going this way till you find the exact extension that makes your computer not boot. Once you've identified the culprit, make sure there's no problem booting with all the extensions on except the suspect one. Depending on what the problem extension is, you may be fine with just running with it disabled, but if it belongs to something you need to use, you'll have to reinstall the software it goes with.
If it doesn't boot properly with the first half enabled, reboot again with the space bar down and disable half of the first half of extensions (so only a quarter of your extensions are running). Basically, you'll be working backwards from the first case, disabling by half until your computer does boot normally, then adding back half the extensions from the last batch you disabled before it worked.
All in all, locating an extensions conflict can be a time-consuming process.