batch?op=start&id=25 . Access denied . warning: Invalid argument supplied for foreach() in ... /includes/menu.inc

batch?op=start&id=25
Access denied

user warning: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '\";i:25;s:1:\"1\";i:26;s:1:\"1\";i:27;s:1:\"1\";i:28;s:1:\"1\";}s:5:\"title\";a:' at line 1 query: UPDATE batch SET token =

warning: Invalid argument supplied for foreach() in ... /includes/menu.inc

I have a problem with my new installation of drupal 6.14 on my server Planet-work.
The basic installation run well, but as soon as I install any module and in particular image-import, taxonomy, admin-menu... I have problem of batch and access denied even if I'm logged with user admin... I can't do anything.

I have also an error warning: Invalid argument supplied for foreach() in ... /includes/menu.inc

I search a lot, in all direction, in all forum, for weeks... And I don't know what to do. I increase the max_allowed_packet on my server as I read in Drupal forum, but nothing has changed.
Do you think that the variables "query_cache_size" (actually set to 128Ko) and "query_cache_limit" (actually set to 128Mo) could cause such problems?
I can't test all settings by myself and I need good argument to persuad my provider to restart the database.

Thanks for your help !