Crazy invisible "locking" behavior of layers

PS CS on Gateway laptop, .75gb RAM, XP - notebook edition

I have a greyscale image of about 26mb with two layers. After working with it for about half an hour, suddenly I can make no changes to a layer. (None of the lock icons in the layers palate are on.) For example, using the eraser has no effect - in fact, nothing does - and no warning messages occur. _Sometimes_ the 'adjustments' menu item also becomes greyed out. The only way to fix this is to make a new layer copy, however after one change in that layer it behaves as if locked... and this goes on forever. (Deleting the old layer is no help, neither is keeping it.)

This has happened only one one file. Changing mode does not help, neither does save-as undere a new name. Oh, and if I save, close and bring the file back and attempt to make a change, the change does not take place, but exiting warns me to save the changes, although none were made.

I'm stumped!

Try reset prefs.

Reset prefs works until the lock happens. I have a similar problem to John's, except it's a jpeg imported from my D100. Sometimes copying works, sometimes resetting prefs, sometimes closing PS7 works, sometimes rebooting. Sometimes it happens with the first image opened; other times I have been editing a whole card of photos (75) and then it'll happen.

John has PSCS, so there goes one reason to not upgrade. adobe.com has the two "fixes" (copy, reset prefs).

wrote in message

Try reset prefs.