Hi, again...
Well, since I installed MsgPlus 5 again, it was working fine, even after restarting the computer many times.
But I noticed something curious.
When I run a registry cleaner, it finds something related to MsgPlus 5.
(I'm attaching the screenshot).
I removed other invalid keys and unmarked the one that leads to "C:\Arquivos de Programas (Program Files)\Yuna Software\Messenger Plus!\Interface\Images" and WLM was still working like before.
When I ran the registry cleaner again and marked the above key and removed it, I got the Microsoft Visual C++ Runtime error. I guess that's the cause of the problem.
When I said that I got this error after restarting the computer, it's because sometimes I run the registry cleaner and restart my system.
If other users also use this kind of programs, try to execute it to make sure if this is the cause of the error.