Photoshop 7 Mystery

Hi, I have been teaching myself PS7 for last couple of years with no problems until yesterday! I have been colourizing B&W photos using Colour Balance Adjustment Layers & Selections, where the Paintbrush masks the selected area and the Eraser reveals colour. Anyway I went on to another project but when I came back to do some more colourizing I found that the Eraser & Paintbrush Tools seem to have reversed functions in Colour Balance Adjustment Layer mode ie the Paintbrush reveals the selected area & the Eraser masks it . Why is this so, have I switched anything on by accident or what?

I haven't got a clue, but have you checked if your brush mode is normal and not behind or clear?

Sounds like you inadvertently switched foreground and background colors. Before you were painting black and erasing to white on the mask layer. Now you're painting white and erasing to black.

hms3001 got it. When you create an adjustment layer, the layer is activated in mask mode. Using the brush tool, you can paint the areas you want to remove or apply this adjustment to. Just toggle between the black(removes the layer adjustment) and white(adds the layer adjustment) colors. You can use the eraser tool to remove the adjustment to certain areas, but its easier just to keep it on the brush tool and toggle the colors using the "X" hotkey.
I don't know how you do your colorizing, but I like to create the color adjustment layer and then goto IMAGE->ADJUSTMENT->INVERT to flip the mask. After I do this, I can use the brush tool and white color to paint in the area I want colored. It works well for me, just thought I would share.
Hope that helps!

Thanks for the help, I have figured out what is happening sort of. When I create a Color Balance adjustment layer to colourise a selected area the Default Foreground & Background colours switch from Black/White to White/Black automatically with even the icon in the corner changing to reflect this (When switching manually back to Black Foreground the icon stays showing White as Foreground). By switching manually back I can refine Masks as I have been doing for sometime with the Eraser deleting parts of a mask and the Paintbrush adding to the size of the mask which is the logical way It seems like I have somehow changed the default Foreground/Background when applied to Adjustment Layers as I just tried using a Curves etc Adjustment Layers with the same thing happening with the defaults changing to White foreground etc automatically. Is there something I have ticked or changed that has made this change