New Post: Chat works only for users having full control or admin rights on SP2013

Hello!

It's not depends on 2010 or 2013...

The problem is inside ContactListUserControl.ascx file.
Line: <link rel="Stylesheet" type="text/css" href="/_layouts/SharepointMessenger/css/<%= ThemeName %>/jquery-ui-1.10.2.custom.min.css" />
Property named "ThemeName" used to get site theme dinamically. So users which is not in Owners or Admins group have not access to site themes.
This is the source of "Access denied" message.

You can fix it in ContactListUserControl.ascx.cs file, within property "ThemeName" declaration or just replace the line in usercontrol with static one,
for example: <link rel="Stylesheet" type="text/css" href="/_layouts/SharepointMessenger/css/classic/jquery-ui-1.10.2.custom.min.css" />

Thanx for product!