Stability of 15 MHz ZipGS

[spec@vax2.concordia.ca (Mitchell Spector)]

   I just replaced my 8/16 ZipGS with an upgraded 15/64 ZipGS (15 MHz! :) 
and seem to have come across as to whether the board is stable or not. 
When launching System 6.0.1, I've noticed the entire system will lock-up 
after a couple of mouse clicks. To be more specific, the mouse-cursor 
still moves around, but everything in the background is frozen (I cannot 
even access the CDA menu, my only option is a Control-Reset at that point).
Just double-clicking on folders, moving a window around, or clicking on
a scrollbar causes a lock-up, within just a few seconds. 

   What's _very_ odd is, doing a shift-boot seems to completely rid me
of these lock-ups. Everything runs smoothly after doing this. I didn't
have any problem with my 8/16 ZipGS, though is it possible (by an 
untimely coincidence) an INIT/DA or setup file become corrupted and
it is not the fault of my new accelerator?

   What should I expect to see if the accelerator were unstable? I would
assume random crashes into Monitor and freezing _regardless_ of whether
I shift-boot, not merely the above problem. One other thing, all software
detects it as 14.93 MHz, not 15.00 MHz. Is this normal? (There's a 60 MHz
oscillator socketed in). 

Mitchell Spector
spec@vax2.concordia.ca