With the introduction of Visual Force Pages for Enterprise and Unlimited salesforce.com clients, on the profile setting users will need the "Enable Visual Force Pages" box checked to launch the Sales Access Manager sheets.
For further details on how to set this up check the training and support link in saleforce.com.
If it is not enabled, a user will see the following error message:
cannot be displayed: You do not have sufficient privileges to access the page:
/apex/(sheetnamewill appear here)