Invalid property id when login

[yiannisK]

I have a strange problem.
When a user login i have error in page (sometimes).
When logsout the error dissapears!!
I was looking for this strange " '  " in line 54 (error) but...
Is a type of database connection problem?!
Info: the problem does not exist on backend

EDIT: The problem is on both xampp and live environments

This is very strange 

[attachment deleted by admin]

[datahell]

Paste here what's in line 54 in the page's html source code.

[yiannisK]

Thanks
Here the html code

Code: [Select]

line: 52>   theme_advanced_layout_manager : "SimpleLayout",
line: 53>   theme_advanced_buttons1 : "bold,italic,underline,bullist,numlist,forecolor,seperator,justifyleft,justifycenter,justifyright,justifyfull,formatselect,fontsizeselect",
line: 54>   theme_advanced_buttons2 : "link,unlink,seperator,image,seperator,undo,redo,seperator,cleanup,hr,seperator,ltr,rtl,seperator,pagebreak,media,abbr,acronym,attribs,help",
line: 55>   theme_advanced_buttons3 : "",
line: 56>   theme_advanced_buttons4 : "",
The problem appears sometimes in line 54 and now in line 56