HP and the store can't identify the problem

System purchased in March 2008. I have spent countless hours talking with HP. I can't accurately position the mouse which is a serious problem. HP finally mailed a new mouse, doesn't help, nor does a new mouse pad, which I purchased.

additionally, I work from home, if i leave the computer idle for more than 20 minutes, the monitor and computer goes to sleep, as it should. However, moving the mouse does not awake the monitor only the computer. The only solution has been to turn off the machine and start over. The store gave me a new monitor two days ago, that has not help. So today, I start over again with the same problems of mouse and sleeping monitor!