FS9 task bar desapearing

Hello,This is happening now systematically when flying online or with ai traffic, I am loosing the task bar of FS9, when there is too many traffic. FSUIPC is set to 25 miles, and SB3 to 25 miles, and under PMDG menu, TCAS is set to FSUIPC and not FS2004, as I am flying mainly online. Note that I am flying in window mode. Clicking on the ALT tab have for effect to have the task bar appearing again, but it is unusable, including with the short cuts.While this is happening, the task bar being on top of the window, the picture on the screen is moved up and on the bottom of the window, I have a balck space wich is exactly the space the task bar would have.Is there any other having the same problem, or just me?As for the standard, question, OS is XP service pack 3, FS9.1, FSUIPC (latest), 3giga patch is applied as I have 4 gig of RAM.Thanks very much for supportCyrille de Lattre