What security role has been assigned to user in CRM whether its a custom or OOB security role?
Can you try assigning any OOB security role then see if issue still persists?
Does user get error while doing set regarding for any particular record or for all records?
Enable Client side tracing to capture error logs for issue and to enable tracing, Go to Start-->Microsoft Dynamics CRM 2011-->Diagnostics-->Advanced Troubleshooting and check the box for tracing.
Let me know, once you have traces for the issue for review. You can collect the logs from C:\users\<user_name>appdata\Local\Microsoft\MSCRM\Logs or Traces.
Regards,
Satish Tiwari
Support Engineer
Microsoft Dynamics CRM