Many Thanks Simon, you have solved my problem Well Done

Thanks for the suggestion but I have the latest drivers installed for Nvidia Geforce GT 340 and
Intel(R) Core (TM) i% CPU 650@3.20 GHz 3.20GHz.
I don't believe there is a problem with Plan-G as I get the same symptoms playing any game when a popup window appears IE skype user going on line or even Volume adjustment with my logitech cordless keyboard.

Can anyone suggest why Plan-G popup messages appear as flashing/shimmering images in FSX.
I get the sound alert OK but the image is unreadable.
OS Windows 7 Home premium 64 bit

Save the .pln file to My Documents/Flight Simulator X files. From the free flight screen in FSX choose flight planner/Load. The file should be in that list. Hope this helps