From Bugzilla Helper:
User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0)

Description of problem:


Version-Release number of selected component (if applicable):


How reproducible:
Always

Steps to Reproduce:
1. Log in with Site Wide Administrator group permissions.
2. Go to Roles tab. Select "First Time Author" role.  
3. Click "Add member". Use Search. Tick "content Administration First 
Time Author" from results. 
4. Click "Add Members" button.
    

Actual Results:  An unexpected error has occurred.

Expected Results:  Automatically returned to Role details screen.
"content Administration First Time Author" now appears in Members 
list.

Additional info:

Can achieve expected results with other members, for 
example, "Heather Fishlock"