Make sure Codec is installed in Windows.
To add all the default codecs in Windows, follow these steps:
1.In the Control Panel, double-click Add/Remove Programs.
2.On the Windows Setup tab, click Multimedia or Sounds and Multimedia, and then click Details.
3.Click the Audio Compression and Video Compression check boxes to select them, and then click OK.
This issue may arise if your network is configured to have both static & dynamic IP address.
Try to make sure all network computer have static IP-Address or
In Outlook Messenger Settings > Network Tab, select the “Default IP Address” option.
In Settings > Other Tab, make sure the "Minimize new popup Chat Windows" option is not selected.
UserName@hostname is the identification used to deliver users Offline messages. If a user is logged in to multiple computers his identification, user@hostname, will be displayed multiple times. You can right click & remove unnecessary offline users. If a user remains offline for three days he will be cleared automatically.
In Windows, you need to enable the Keep Alive setting for Terminal Service Users, since when Idle, TS will be in disconnected state.
Details regarding keep alive :
In your Outlook Messenger Settings, make sure the "Microsoft Outlook Plug-in" option is selected.
If it is already selected, unselect it, and click Apply.
Re-select the"Microsoft Outlook Plug-in" option and& click Ok.
For Outlook 2000, XP, 2003: You can also try removing the Outlook Messenger Plug-in (Microsoft Outlook, Tools >> Options >> Other>> Advanced Options >> COM Add-ins, Uncheck & Remove "Outlook Messenger") and then enable the Settings option again.
Due to security software or Windows User rights, Outlook Messenger is unable to save the license key in the registry. Try to register by logging in as an Administrator.
You need to exit Outlook Messenger before uninstalling.
In Microsoft Outlook, Tools >> Options >> Other >> Advanced Options >> COM Add-ins, Uncheck & Remove "Outlook Messenger"