Check out this link:

http://support.microsoft.com/default...b;en-us;213904
XL: Error Message: Too Many Different Cell Formats

to explain what's happening and how to get round it.

Hope this helps.

Pete

On Mar 23, 10:04 am, vijaydsk1970
wrote:
i have a excel file which contains more than 20 work books and each is
interelated with each other.
recently when i am adding some comments in one of those sheets i am getting
the following message
"no more new fonts may be applied in this book"
can any one help me out.