dva270

I have a problem,I start my IFR flight and everything goes well until TOD.As soon as I get the descent clearence from the fsx atc I: cannot click left or right anymore hear a sound when I press a key ("windowsXP Ding.wav") can still use my yoke and rudder pedals The problem is that I can not control my descent because the AT is on and is still set for cruise.I can get the autopilot off by pressing " Z " but I cannot aknowledge atc anymore or use my FMC, AP, AT etc.When this occurs, I press " Escape", then the Window does appear normaly but also here I can't click anything.I usually use ALT+TAB to swith to my desktop and then use taskmanager to quit fsx, since that's the only way.Is anyone familiar with this problem or does anyone know how to solve it?My computer specs are: CPU: Intel e8500 @3.16 Mem: 4GB ddr2-800 Grphx: nVidia gt9600 Motherboard: Asus p5n-d HD: 7200rpm 500gb power supply: 850w OS: Windows XP proffesional SP3 32bit All my drivers are up to dateFurther used: Saitek Proflight Yoke Saitek Proflight Rudderpedals I use FSX SP2 with the following addons: FSacars FSUIPC UTX europe REX 2.0 GEX europe MYtraffic X 5.2 ariane 737-800 X2 advanced level-d 767 Pmdg md11, 747 and j41 carenado piper saratoga captain sim 757 Thanks in advance!Kind regards,dva270