Many times this is the result of too many background programs running. I have had this problem, and the only way to eliminate it is to stop running any unnecessary background programs that may come with your machine. Dell and Gateway and other manufactures put programs like AOL subscription options or machine maintenance programs in the background.
The place to remove the unnecessary programs is in msconfig. You have to be careful, however. If you do not know what you are doing, you could stop some necessary programs that make your machine and operating system effcient, or capable of running in the first place. Before making any changes to msconfig, I would first make a current "System Restore" setting. That way, if you get into trouble, you can use system restore to restore your computer to the original settings. I would also make a list of startup programs currently checked in msconfig so that you can recheck them if you run into trouble.
Press the "Start" tab, and press "run". Type in "msconfig", and then go to the "Startup" tab. Uncheck any programs that you think is not necessary, press "apply" and "OK". Restart your computer.
Charles