New users not being added to main blog in WordPress network setup

Running 3.1.4 in Network mode, subfolders (not subdomain). When a new user registers, they are not being assigned to the main blog/site (ID 1). If I look up the user in the User Management area, they have no assigned sites. If they attempt to log in after activation/verification, they are presented with the “Global Dashboard” with no sites listed. However, if they then visit the main site while logged in, they are suddenly added to the main site. From what I can tell from the documentation, new users SHOULD be added to the main site.

I do have debugging enabled currently and noticed the following when a user registers:

[10-Nov-2011 09:14:00] PHP Notice:  Undefined property:  WP_User::$wp_1_capabilities in /sites/umcuawebcom/wwwmizzouadvantage/wp-includes/user.php on line 734
[10-Nov-2011 09:14:00] PHP Notice:  Undefined property:  WP_User::$wp_1_capabilities in /sites/umcuawebcom/wwwmizzouadvantage/wp-includes/user.php on line 734

line 734 is where Wp is inside function is_blog_user(). When the new user activates/verifies their registration, the following error is thrown:

[10-Nov-2011 09:18:50] PHP Notice:  Undefined index:  add_to_blog in /sites/umcuawebcom/wwwmizzouadvantage/wp-includes/ms-functions.php on line 1863
[10-Nov-2011 09:18:50] PHP Notice:  Undefined index:  add_to_blog in /sites/umcuawebcom/wwwmizzouadvantage/wp-includes/ms-functions.php on line 1863

1863 is inside the function add_new_user_to_blog().

Any ideas on what might be causing this? I can start dumping additional debug data in those areas, but am hoping someone has some ideas that will save me some time in debugging this issue.