.. run antivirus scanner(s) [not at the same time, of course]. If there's a virus chances are it will be caught.
Other than that you 'might' be having driver problems (as I was having when the start bar would loop in Not Responding). So download the newest drivers for your Dell @ the Dell's driver download center.
My computer has been having some problems lately, as you may now have figured out. A few days ago my laptop was working fine, but now applications randomly go "Not Responding". For instance, I was just typing this in Mozilla Firefox and it started "Not Responding". If I try to switch to anything else, i.e. Microsoft Word, Thunderbird, even opening the start menu or right clicking on the desktop, those applications also go "Not Responding". Sometimes the applications fix themselves in about 5 minutes, other times a manual restart is necessary. My CPU according to task manager is about 4% (aka not spiking to 100%). I tried booting in safe mode and it seemed to revert to normal settings each time.
So cnet...I was just wondering if you knew what the cause of this problem is...hard drive? Processor? Software/virus? Even better would be how to fix it, if I can do it without taking into the shop. Any feedback would be greatly appreciated, as I nor any of my tech-friends have encountered this type of problem. Thanks!!