DCS Black Shark, gui as well as sim was crashing frequently to desktop with the crashlog to Microsoft showing an error in directinput8.dll
Here's the system:
processor C2D 8500
4 GB ram
windows XP SP3
ATI 4870
CH fighterstick, throttle, and rudders
USB audio for voice comms
usb mouse/keyboard connected via a KVM switch
Microsoft Sidewinder USB gaming Mouse
And here's a work around:
Changing connected USB devices, say using the CH manager for the joysticks or by disconnecting the USB audio decreased/increased crashes - reducing the number of devices always seemed to help.
Disconnecting the Sidewinder mouse from the system has so far eliminated all crashes.
Perhaps this is one for the devs to investigate as this has only ever happened for me in DCS (not lomac or flaming cliffs).