Overview:

Error: Insufficient Privileges - When viewing a child account from the related list on account page in Online CRM. 

Root Cause:

The View button is replaced by Visualforce Page View Child Account2 [View_Child_Account2_vod]. However, the user does not have the access to that Visualforce Page. 

Solution:

Grant the end-user access to the Visualforce Page.

1. Navigate to Setup.
2. Find Profiles in the quick search bar and go to Manage Users --> Profiles.
3. Select the user's profile.
4. Click the Edit button on the enabled Visualforce Page Access section.
5. Add the View_Child_Account2_vod Visualforce Page.

Related Documentation:

CRM Online Help: Working with Child Accounts