Fatal error: Allowed memory size of 16777216 bytes exhausted

Everytime i install a new module i get this:

Fatal error: Allowed memory size of 16777216 bytes exhausted (tried to allocate 185966 bytes) in /webroot/vhosts/xxx/docs/drupal/includes/database.inc on line 159

Warning: Table 'watchdog' was not locked with LOCK TABLES query: INSERT INTO watchdog (uid, type, message, severity, link, location, referer, hostname, timestamp) VALUES (1, 'php', 'Table 'sessions' was not locked with LOCK TABLES\nquery: SELECT sid FROM sessions WHERE sid = '2ea56ecd358c1ef728d1a1c64041c63e' in /webroot/vhosts/paradise-bodies.com/docs/drupal/includes/database.mysqli.inc on line 151.', 2, '', 'http://www.paradise-bodies.com/drupal/admin/build/modules/list/confirm', 'http://www.xxx.com/drupal/admin/build/modules', '87.167.115.207', 1202714659) in /webroot/vhosts/paradise-bodies.com/docs/drupal/includes/database.mysqli.inc on line 151

Warning: Table 'watchdog' was not locked with LOCK TABLES query: INSERT INTO watchdog (uid, type, message, severity, link, location, referer, hostname, timestamp) VALUES (1, 'php', 'Table 'sessions' was not locked with LOCK TABLES\nquery: INSERT INTO sessions (sid, uid, cache, hostname, session, timestamp) VALUES ('2ea56ecd358c1ef728d1a1c64041c63e', 1, 0, '87.167.115.207', 'form|a:37:{s:32:\\"33b01945ae647be72f4c8ec7d2852810\\";a:2:{s:9:\\"timestamp\\";i:1202654196;s:4:\\"args\\";a:1:{i:0;s:14:\\"system_modules\\";}}s:32:\\"8688b8382f9f8ec4504e163f77d00bf0\\";a:2:{s:9:\\"timestamp\\";i:1202654229;s:4:\\"args\\";a:1:{i:0;s:14:\\"system_modules\\";}}s:32:\\"dc9f513b7bf8aae10ccdfe in /webroot/vhosts/xxx/docs/drupal/includes/database.mysqli.inc on line 151