maybe a silly question, but did you actually click on the sheet name itself (ie not on the sheet somewhere)? are all the sheet tabs white or is just one white and the others grey? if they are all white it should mean that the sheets are grouped, and by right clicking on the sheet tab you'll get a shortcut menu, the top item of which will be 'ungroup sheets'. if you don't get this on the menu it probably means your sheets aren't grouped but if that's the case,beyond sheet corruption or some vba code (you can see this by right clicking on the sheet tab and selecting 'view code' from the shortcut menu) which is making it behave this way i can't see why this is happening.