Need Photoshop help

[Analog6]

I'm using CS4, I always do my edits in layers and rub out the bits I don't want with the eraser. Suddenly, it will not let me do that in the Vibrance layer, although I can still do it in the high pass layer. I'm not getting any message, it's just not working. Have I done something that has suddenly made it different?

The computer did an upgrade last night but it was from Apple not Adobe.

Help, any tips most appreciated.

[Big Pix]

are you working on a background layer or layer 0

Double click on the background layer and go OK..... it will rename the layer ...... you should be able to do what you want now....

[Lani]

A more reversible way than using the eraser is to use layer masks and brush tool. I wonder if that would fix the problem?

[Analog6]

Not working in Layer masks either. Just get white and white, no black. Can't paint on the mask. I've obviously pressed some combination of keys by mistake. Is there a reset all option?

[Big Pix]

on the left in the tools are your little squares set to default, just click on the little black and white squares...... and caps lock off on the key board

[Analog6]

How do I check if it default? I clicked that square and circle on the bottom (I have them in a strip on my Mac) and it started giving me red no matter what I do, in my mask it painted red over it - does not do a mask at all. If I use the eraser it paints red over it! Very frustrating