It's not that I forgot how to operate the program (heck I can remember how to use IconGraphix on the spectrum), but rather the creative process I had has gone. These programs have different toolsets and make you build up a picture in different ways.
I've just gotten so used to the Photoshop way (with layers, transparencies and 24bit) that I just can't think how to build a picture in terms of brushes, palettes, and 256 colours.
but you guys are right, it should be a matter of practice, after all it took years to get where I was with PPaint before. I just hope it doesn't take years to remember. :-o