Problem with exxpand and collapse in admin content pages

[mebots]

Hello,

in admin page content -> pages -> Expand and Collapse not working.

The error is in xajax_core.js line 395.

uncaught exception: [object Object]

thanx,

Martijn

with here my config:
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Cms Version: 1.11.2

Installed Modules:

CMSMailer: 5.2.1
CMSPrinting: 1.0.3
FileManager: 1.4.1
MenuManager: 1.8.4
MicroTiny: 1.2.3
ModuleManager: 1.5.5
News: 2.12.9
Search: 1.7.7
ThemeManager: 1.1.7
CGExtensions: 1.31.1
SiteMapMadeSimple: 1.2.6
TinyMCE: 2.9.11


Config Information:

php_memory_limit:
process_whole_template:
output_compression: false
max_upload_size: 10000000
url_rewriting: mod_rewrite
page_extension: .html
query_var: page
image_manipulation_prog: GD
auto_alias_content: true
locale:
default_encoding: utf-8
admin_encoding: utf-8
set_names: true


Php Information:

phpversion: 5.3.8
md5_function: On (True)
gd_version: 2
tempnam_function: On (True)
magic_quotes_runtime: Off (False)
E_STRICT: 0
E_DEPRECATED: 8192
memory_limit: 128M
max_execution_time: 90
output_buffering: 4096
safe_mode: Off (False)
file_uploads: On (True)
post_max_size: 10M
upload_max_filesize: 10M
session_save_path: d:/tmp (0777)
session_use_cookies: On (True)
xml_function: On (True)
xmlreader_class: On (True)


Server Information:

Server Api: cgi-fcgi
Server Db Type: MySQL (mysql)
Server Db Version: 5.1.65
Server Db Grants: Found a "GRANT ALL" statement that appears to be suitable


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[Dr.CSS]

What browser..?

[mebots]

In all browsers (IE9 firefox, safari, chrome, etc) tested, it looks like it has the do with the sessions or something.