It sounds to me like a dialog for the filter you choose, in your example the unsharp mask, is opening off your screen.
Have you had or do you have dual monitors?
I'd try resetting the photoshop 7 preferences:
Hold down Shift+Alt+Ctrl just after launching ps7 and keep holding those three keys down until you get a dialog asking if you
want to delete the photoshop settings file. Press Yes because you do.
Terrific you were spot on. I follwed your advice and now at last it works normally
Yes I have had dual monitors.
I'm so grateful that you shared your wisdom with me.
Update Photoshop to 7.0.1, no one should be using 7.0.
Many bugs were fixed in 7.1.