FSG reports not being generated which have up to 90 worksheets in them

Hello Experts,

Business Requirement:

Has FSG reports being generated which have up to 90 worksheets in them. 

When using Report Manager to publish find that a single page (branch) can be published in Excel 2010 with no problems,
but when select ALL in the Expansion Value the report only generates a few of the worksheets before Excel stops responding. 

Different pcs result in different numbers of worksheets being generated - the maximum being 20 sheets before freezing occurs,
whilst other pcs consistently generate either 5 or 7 worksheets only.

Business needs to be able to generate the Excel file with all worksheets available.

Any suggestion would be greatly appreciated.