I am also running A Dell Inspiron and for several weeks the Logitech Wireless USB 2.0 TrackBall Mouse and Keyboard worked well
.. The Wireless connect point was connected to the Dell via a USB Hub.
Then without warning, the cursor started moving on its own or not releasing an icon if changing between icons
.. When shutting down I would get a message stating SOMETHING could not close because it was still in use, although nothing I knew of was active. I did everything that has been suggested with no luck
.. Dell suggested I RUN MSCONFIG STARTUP and disable everything and reboot. This brought back my touchpad use. I then enabled things that I needed or knew were not a conflict. While this was informative it did not pinpoint the problem.
When I reinstalled the USB Hub with the wireless access point attached the problem reappeared.
Isolating the mouse problem, I went back to the Wired Keyboard via USB hub and the Wiresless mouse and so far so good. The Wired Keyboard and Wireless access point are now in seperate ports on the USB hub.
It seemed to be a conflict between the twowireless devices and the touchpad.