Thanks for the reply,
Yes it is the quick mask option and it is something I use quite a lot, but now it is as if I have selected a channel and am only masking either the green, red or blue channel instead of all three (this is a guess) I have even removed
PS from my computer and reloaded it and it is still the same....
This happened after I tried a few shortcuts on the keyboard, but I can't find the cure - Nothing seems simple on my computer as it was rebuilt after a crash and I couldn't find the application data to delete the preferences - I tried the alternative method by pressing Alt shift delete when starting up and this seems to have cured it!
Thanks very very much -I had almost pulled out what hair I had left!
Cheers
Frank