Problem with buttons ('x's) for closing activities from dashlets

[LaFortuna]

Hi, within a new installation (6.1.4) we are no longer able to close activities (tasks, calls, meetings) by using the little close buttons (x's) in Home dashlets or in the Activities' subpanel in Contacts, Accounts or Opportunities.
The install is running on Apache 2.2.17 with PHP 5.2.15.

I get this error when trying to close the activity with IE:

Webpage error details

Message: 'undefined' is null or not an object
Line: 585
Char: 132
Code: 0
URI: http://[domain]/crmtest/include/javascript/sugar_grp1.js?c=1

Thanks for your help!:

[item]

Hi,
i have too these kind of problem. for a good help or a good analyse, can you provide some information about your environement :

- language pack installed ?
- explorer ? Firefox try ?
- custom field create ?
- customize layout ?

Hope we can find where come this problem.
For me i suppose a customisaion or language pack but i have not still found

Cheers

[LaFortuna]

Hi, I have Spanish installed and it has also caused me troubles in the past (i.e. Not being able to use the layout editor in studio while in Spanish).
I have several custom fields but mostly text only, nothing fancy.
The only other custom module I installed was Login Audit.

Any clues?