In device manager is there a yellow warning dot on your Joystick? Does it list under its name or generic game device?
If it's your XP registry calibration settings try this from Logitech to completely clean out any controller calibration settings in your registry:
http://www.logitech.com/en-us/441/291?softwareid=633&osid=1§ion=downloadsI'm going to assume no XP updates installed recently have changed your power management or USB power management. But. just in case go into the screen saver tab and turn off all power management. Under devices go into USB controllers and your joystick device and turn of allowing the OS to turn off this device for all of the root HUBs and your joystick which should be higher up in the device tree.
Are you running a screen saver? Turn that off and see if this stops. Do you have other USB devices connected to your PC other than a throttel, mouse/keyboard? Have you pulled those other devices? Plugged your joystick into a different port?
DIView can tell you alot about your joystick while it's just sitting idle in windows before you start the game. Is it sitting there spiking on the x, y axis or off center on both? What joystick is this? Have you run searches against your joystick and XP to see if other people have your problem? Have you swapped out your joystick to see if it's the joystick?
Two possible reasons why Skuzzy hasen't hopped in yet.
This should have been posted in the techsupport section along with your joystick type and PC info. Or there is no simple XP solution and he's letting me run through the general question and answer with you to build up a picture of your problem or solve it.
What have you done to troubleshoot this yourself so maybe I don't reinvent the wheel.