Shoutbox

I am currently using:
Windows Live Messenger 2011 (Build 15.4.3538.513)
Messenger Plus 5.10.0.748 (Released 20/9/2011)
Windows 7 x64 SP1

Problems:
When i try send a message by starting a new conversation, once i press "Enter" key to send the message then it will immediately show me "The following message could not be delivered to all recipients". (FIGURE 1)

This problems occurs for only one contact, i can send message to other remaining contacts.

However when this contact send me a message, i am able to reply him without any problems.

*This problems no longer exist when i uninstall MSGPlus.
*However when i try to install MSGPlus back, this problems occur again with the same contact person.

What i have tried:
Reinistall WLM
Reinstall MSGPlus
Clean registry with CCleaner, Tuneup Utilities 2011

And still only that contact has the problems with MSGPlus.... T_T

Thanks in advance for help~~ ^^

FIGURE 1: