Open Manage | database | fields, find the field definition for the field where editing a value pops up the validation message and remove the validation field option responsible.
But which field has this setting isn't always obvious and there are ways to have a message similar to a validation error message pop up via a script performed by a script trigger.
You may have a field with an auto-enter calculation that references the field you edited that also has a validation field option. So editing the first field trips an error in the second.
thanks. your suggested had me relook at the settings. I had doubled references to the values list in the manage database and again in the layout. removed the auto enter aspect and the bothersome notification went away. Thanks.