Seems as you plugin have an error.. When a plugin errors on a reload, MsgPlus! will untick it from the list... Thereby it will not be loaded...
You might want to check your code through...
Is it in VB?... If yes, then I suggest you do not use "On Error Resume Next" or "On Error Goto xxxx" if you have used that code?....
Edit: Btw, welcome to the forum..