I have a VB app calling methods in an object created in an .EXE automation server (written in C++ MFC). Two different VB forms are accessing two different objects in the same .EXE server. In general, things work fine, but I seem to get occasional collisions when both VB forms are accessing the server and one reports an automation error 0x8001005 ("Illegal to call out while inside message filter"). The one reporting the error is being wakened by a timer to make periodic calls (which work most of the time). How is this caused and can it be avoided?