SharePoint V3 have a serious problem, the new added user can not be assign correct rights, except assign full control to the new user. Here is the way to assign read only rights.
Step 1: Logon new user account; then from intranet error page, click “web parts maintenance page”. Then click “Request access” link, and send the request.\
Step 2: Logon as administrator, open the email, click second link “Grant domanName\n.user access to the site”, give the full control rights on this new user,
Click third link “Manage request access setting for the site”, click “OK” button to allow the user access intranet.
Step 3: Logon new user account, re-open IE, it still show a error page, click “web parts maintenance page”, then you can see a “web part page maintenance: default” page.
On top menu tab, click “document and lists”, then look at left side menu, click “Intranet Event”. Now you got a error page, shows “access denied”. Click “request access” and send the request.
Step 4: Go back administrator account. You got a new email, click “Grant domainName\n.user access to the list or library” link. (Notes: the fist email showed access whole site, but this one show as list). Assign read-only right.
Step 5: Go to new user account, popup IE, now you can see the correct master page.
Step 6: This is important, you have to setup new user has read-only right from administrator account. Go back first email, click the send link again, assign read-only rights on the new user.
Step 7: By new user account, open intranet, double check this users right. Make sure it doesn’t have full control. That’s all!