Your XOOPS version is 2.0.18. It is not compatible with pico. That's the problem I guess.
http://www.nhatban.net/info/a0021.html
Fatal error: Call to a member function on a non-object in /var/www/html/search.php on line 211
@avtx30 : for your mail conf page blank page, I too had a problem like yours.
It was due to the fact that our site had "too much" users for the XoopsFormSelectUser form...that is used only in this configuration page (check the "config" table, and you'll see that only this page has "user" value in "conf_formtype" field).
So, to solve this, the proper way would be to replace the XoopsFormSelectUser form by the "custom" one use in the Edit user page (this one uses pagenav to split user list every 200 users, so there's no crash).
I didn't do this myself yet (we simply hardcoded the right value in the table and made the selectuser form disapear, since we hadn't time/need to correct this better), but I think it can be quite easily done.
Sorry not to have reported a bug about that yet, but I wasn't able to reproduce it outside of my job to get more details (it need to have more than 200 users in the site to occur, and I was too lazy to create false ones on my dev sites ;o) )
Hope it'll help !