Need help - lock ups

[Jank]

OK, I'm out of ideas.
Just last month I installed USB printer/scanner/copier. I had some problems doing it - had to scanreg/fix.
Since then - frequent lockups - windows protection errors, memory errors, disk drive errors....have to fix registry daily, scan drive daily...
Installed extra 128Mb of RAM - hoping for miracle - same.
Tried some diags, could not find anything. Sometimes it locks up without Win running - when playing with BIOS !
Re-installed Win98SE - worked for a day or two - problems are back now.
Moved virtual mem to my other disk - same thing.
Took the CPU down to default - 450MHz - seems better, not sure yet.
What's up ? CPU, RAM ( passes test ), BIOS ?
Is there a diag s/w I can download to help me with troubleshooting ?
Anything you guys recommend ?
And if I go for new CPU - what can I just plug in without a slotket ?
ABIT BE6 - slot 1 (100 MHz)running PIII 450.
Anything will be appreciated.
I copied this from h/w forum - no replies yet.
Today I got a message to increase MInSP in system.ini - what is this ?