Os 9 Optimization For Audio Resulted In Freezes Etc.., Crashes/ freezes after attempted Optimization/tweeks. Options

[Apesounds]

Right, first off, cheers to the people who have already offered invaluable advice thus far on these forums, appreciated lots:)

Right, basically I was endeavouring to Optimize my Mac g4 OS 9.2.1 for use with audio and more specifically Cubase 5.
I followed some basic 'Optimum settings for Cubase on a mac' procedures in the following order.....
1. Apearance control panel : Changed font to Chicago, disabled 'smooth all fonts on screen' option..
2. Altered Memory allocation for Cubase to 200mb as stated....
3. Under Sound control panel set Soundtrack to None.
4. Appletalk was switched off in AT Control panel.
5. Date and Time panel, disabled 'Use a Network time server', and set the time from 5;15 to 4;15,(don't think thatd be relevant but you never know)....
6. Energy Saver I switched sleep option to Never.
7. File sharing was off in FS Control panel.....so didn't need to alter that...
8. Memory control panel, switched Virtual Memory off and Ram disk to off.
9. Finally I set the Monitors Control Panel to 'Thousands' of colours as opposed to Millions.

Essentailly I had OMS, Cubase 5 and a Tascam 428 all installed and conversing with each other apparantly without problem, since doing the above the following is occuring.....

Finder Keeps quitting and telling me to restart, which I try however it freezes mid startup.
Attempted to access Memory Control panel and got an Unexp'td error of type 2 (memory I believe?)......
Now whenever I start up the Mac the OS boots and loads to the point of desktop appearing, all desktop elements (Hardrive1/ folders etc) then vanish and I'm left with a frozen mac....which I try to restart and well, sure you get me......

I don't want to format the HD AGAIN and reinstall everything, however I'm now essentially left with an unbootable OS and even if it did load or work I don't know what it is I've done in order to deserve such occurences/ errors....
If anyone has any idea of either a: What I've done or b: How best to go about sorting, it'd be mostly appreciated, cos I feel like I'm going round in circles.
Any 'proper' links to Optimization techniques would be a bonus.....

Cheers to anyone who actually reads this essay:)
Carl.