Does anyone know how to get around this sybase error

Database error code: 414
Database error message:
Select error. The current query would generate a key size of 456 for a
work table.
This exceeds the maximum allowable limit of 256.

It is a simple select of about 25 columns with 3 order by columns ( sum
of their size 62 )

We are running Sybase System 10 on Windows NT

Any help appreciated