After update zabbix(server, agent, frontend) to 1.8.13 version i can't open zabbix admin page via http. Browser waiting for server and MySQL log write:

11 Query SELECT g.usrgrpid FROM usrgrp g, users_groups ug WHERE ug.userid = 2 AND g.usrgrpid = ug.usrgrpid AND g.users_status = 1 LIMIT 1 OFFSET 0
11 Query SELECT s.* FROM sessions s WHERE s.sessionid='c2a43d7d3460b641ef88311c3a76cd8e' AND s.status=0 AND ((s.userid BETWEEN 000000000000000 AND 099999999999999))
11 Query begin
11 Query DELETE FROM sessions WHERE status=1 AND userid='2'
11 Query UPDATE sessions SET status=1 WHERE sessionid='c2a43d7d3460b641ef88311c3a76cd8e'
11 Query SELECT u.* FROM users u WHERE u.alias='guest' AND ((u.userid BETWEEN 000000000000000 AND 099999999999999))
11 Query INSERT INTO sessions (sessionid,userid,lastaccess,status) VALUES ('26298f63aec8a3eb0431fbdc1ceba241',2,1338274572,0)
11 Query SELECT MAX(g.gui_access) as gui_access FROM usrgrp g, users_groups ug WHERE ug.userid=2 AND g.usrgrpid=ug.usrgrpid
11 Query SELECT g.usrgrpid FROM usrgrp g, users_groups ug WHERE ug.userid = 2 AND g.usrgrpid = ug.usrgrpid AND g.users_status = 1 LIMIT 1 OFFSET 0
11 Query SELECT s.* FROM sessions s WHERE s.sessionid='26298f63aec8a3eb0431fbdc1ceba241' AND s.status=0 AND ((s.userid BETWEEN 000000000000000 AND 099999999999999))
11 Query DELETE FROM sessions WHERE status=1 AND userid='2'
11 Query UPDATE sessions SET status=1 WHERE sessionid='26298f63aec8a3eb0431fbdc1ceba241'
11 Query SELECT u.* FROM users u WHERE u.alias='guest' AND ((u.userid BETWEEN 000000000000000 AND 099999999999999))
11 Query INSERT INTO sessions (sessionid,userid,lastaccess,status) VALUES ('961d48a3d2d04a086f5d0827ec88a300',2,1338274572,0)
11 Query SELECT MAX(g.gui_access) as gui_access FROM usrgrp g, users_groups ug WHERE ug.userid=2 AND g.usrgrpid=ug.usrgrpid
11 Query SELECT g.usrgrpid FROM usrgrp g, users_groups ug WHERE ug.userid = 2 AND g.usrgrpid = ug.usrgrpid AND g.users_status = 1 LIMIT 1 OFFSET 0
11 Query SELECT s.* FROM sessions s WHERE s.sessionid='961d48a3d2d04a086f5d0827ec88a300' AND s.status=0 AND ((s.userid BETWEEN 000000000000000 AND 099999999999999))
11 Query DELETE FROM sessions WHERE status=1 AND userid='2'
11 Query UPDATE sessions SET status=1 WHERE sessionid='961d48a3d2d04a086f5d0827ec88a300'
11 Query SELECT u.* FROM users u WHERE u.alias='guest' AND ((u.userid BETWEEN 000000000000000 AND 099999999999999))
11 Query INSERT INTO sessions (sessionid,userid,lastaccess,status) VALUES ('65a223f1d3119078f4fd3a521e3c16be',2,1338274572,0)
11 Query SELECT MAX(g.gui_access) as gui_access FROM usrgrp g, users_groups ug WHERE ug.userid=2 AND g.usrgrpid=ug.usrgrpid
11 Query SELECT g.usrgrpid FROM usrgrp g, users_groups ug WHERE ug.userid = 2 AND g.usrgrpid = ug.usrgrpid AND g.users_status = 1 LIMIT 1 OFFSET 0
11 Query SELECT s.* FROM sessions s WHERE s.sessionid='65a223f1d3119078f4fd3a521e3c16be' AND s.status=0 AND ((s.userid BETWEEN 000000000000000 AND 099999999999999))
11 Query DELETE FROM sessions WHERE status=1 AND userid='2'
11 Query UPDATE sessions SET status=1 WHERE sessionid='65a223f1d3119078f4fd3a521e3c16be'
11 Query SELECT u.* FROM users u WHERE u.alias='guest' AND ((u.userid BETWEEN 000000000000000 AND 099999999999999))
11 Query INSERT INTO sessions (sessionid,userid,lastaccess,status) VALUES ('2473825d198ddb5fb4b8eaf74e37e2ea',2,1338274572,0)
11 Query SELECT MAX(g.gui_access) as gui_access FROM usrgrp g, users_groups ug WHERE ug.userid=2 AND g.usrgrpid=ug.usrgrpid
11 Query SELECT g.usrgrpid FROM usrgrp g, users_groups ug WHERE ug.userid = 2 AND g.usrgrpid = ug.usrgrpid AND g.users_status = 1 LIMIT 1 OFFSET 0
11 Query SELECT s.* FROM sessions s WHERE s.sessionid='2473825d198ddb5fb4b8eaf74e37e2ea' AND s.status=0 AND ((s.userid BETWEEN 000000000000000 AND 099999999999999))
11 Query DELETE FROM sessions WHERE status=1 AND userid='2'
11 Query UPDATE sessions SET status=1 WHERE sessionid='2473825d198ddb5fb4b8eaf74e37e2ea'

...this continues until the end of the memory in PHP.
Finally browser shows empty page.