PHP Fatal error, when accessing ?q=admin

This is what I get when I try to access ?q=admin :
Fatal error: Allowed memory size of 16777216 bytes exhausted (tried to allocate 143 bytes) in /foo/bar/public_html/sites/all/modules/custom/views/modules/views_user.inc on line 386
or:
Fatal error: Allowed memory size of 16777216 bytes exhausted (tried to allocate 23040 bytes) in /foo/bar/public_html/sites/all/modules/custom/views/modules/views_user.inc on line 422

Otherwise, it's ok when I access ?q=admin/* or any other path.
Also on my local machine I have no problems.

I may be able to increase PHP's memory limit (which I already did and it seems to work fine), but what's the connection between views and the administration section, and why does this happen only in ?q=admin, but not in ?q=admin/* ???