how mine worksheets do you have in the workbook? if you get to mine and you dont have a nuff ram or processor will not be able to open it. But don’t think there is a limit no how mine you can hide, but if you are at a point were it will not let you hide any more then, may be your workbook is at a limit for excel for reading it no how huch you tryed to hide.
ahh - that is different. Take a look at this
http://support.microsoft.com/kb/211769