Minimum Dynamics CRM Permissions

Please refer to a good post regarding setting minimun permissions for MSCRM

http://www.orbitone.com/en/blog/archive/2009/10/06/minimum-dynamics-crm-permissions.aspx

This covers the following scenarios:
First login
Create an Activity
Track an Activity in CRM
Send Mail Merge Letters
Create Queck Campaign
Create Reports with Report Wizard
Use Custom Entities
Run Automatic Workflows
Deletion of Records – The Rule and The Exceptions

Even if the above post does not help you, then try the following:
1> Enable Tracing for CRM.
2> Then use Stunnware Tools for Microsoft Dynamics 4.0 to read it in grid form.
3> Check which privilege id is highligted in the error message.
4> In SQL write the query "select name from Privilege where PrivilegeId='GUID' " to get the security role name.
5> Go to security role in MSCRM that the user is having.
6> Provide the permission required.

You may download CRM tools from
http://vidmar.net/weblog/archive/2010/05/06/ultimate-dynamics-crm-tools-list.aspx