Probelms with PS CS5 - Cant add a transparent gradient layer mask to a layer - please help

Question

My company just upgraded us to cs5 on our macs. I was working along in photoshop & dont know if I hit something inadvertently or what but all of a sudden I cannot add a black to transp gradient to a layer mask. Ive searched around even saved out and re-loaded the gradients from my pc (which has the black to transparent gradient in the gradient editor & the process works fine).
Funny thing is that in the mac gradient picker, the black to transparent gradient is black and solid white but the name of it is 'black to transparent' in the editor. Ive tried
I guess my questions would be how would one make a transparent gradient, or how would one reset the gradients to default becuase every time i delete all the gradients the add a new .grd file from my pc, it still does not show the gradient.
Its amazing how such a small thing like this saves so much time and its eating me up that I cant get this to work
Thanks in advance, Mark

Answer 1

C:\Users\User\AppData\Roaming\Adobe\Adobe Photoshop CS4\Adobe Photoshop CS4 Settings
This is where I finally found the prefs.psp file.  At least this is the way my Vista machinie is set up.  Your "User" config may be diferrent from mine.
But, Thanks for the right answer!.  My transparent layer is now only showing the faint gray checkboard instead of black.
Rob_L