I am having the exact same issue on the exact computer. It's NOT viruses or Malware. It has something to do with the factory install, and the factory settings. I have two of the Dimension 3000's, and on one, I reinstalled Professional, and it works fine now. The other computer, I actually kept on using although it was SLOWER THAN you can possibly imagine. I did a Factory Restore, and it was then that I remembered how much JUNK Dell had on my computer when I first got it. First of all Norton is horrible. Period. When the computer booted up, it was working normally. As I started to uninstall some of the programs that were uneeded, it went right back to what is was doing before, and it DRAGGED like no other. I'm fixing to install a clean version of Professional on there, and if that doesn't work, it's going in the dumpster. I've been doing this for a decade, and computers take the cake when it comes to unexplainable bullsh*t.

Hey if you end up needing to open up your case there are some great repair manuals here.

http://www.laptopmanuals.com

Dell Latitude c500-c600 3.8 mb
Dell Latitude c400 1.9 mb
Dell Inspiron 9100 4.6 mb
Dell Inspiron 7000 6.6 mb
Dell Inspiron 8500-8600 3.7 mb
Dell Inspiron 8200 4.7 mb
Dell Inspiron 8100 4.1 mb
Dell Inspiron 8000 1.6 mb
Dell Inspiron 7500 1.3 mb
Dell Inspiron 3700 2.5 mb
Dell Inspiron 5000 2.7 mb
Dell Inspiron XPS 9100 4.6 mb
Dell Inspiron 4150 4.0 mb
Dell Inspiron 4100 4.7 mb
Dell Inspiron 4000 2.6 mb
Dell Latitude c510-c610 2.9 mb
Dell Latitude c540-c640 2.8 mb
Dell Inspiron 3800 1.3 mb
Dell Inspiron 1100-5100-5150 3.5 mb
Dell Inspiron 2100 series 3.9 mb
Dell Inspiron 2600-2650 4.4 mb
Dell Inspiron 3000-3200 3.9 mb
Dell Inspiron 3500 4.9 mb
Dell Latitude D500 3.4 mb
Dell Latitude D400 2.6 mb
Dell Latitude CS 3.7 mb
Dell Latitude cpx H-J 7.3 mb
Dell Latitude c800 3.8 mb
Dell Latitude C810 3.3 mb
Dell Latitude C840 3.7 mb
Dell Latitude cp,cpi 8.1 mb
Dell Latitude cpi-R 5.0 mb
Dell Latitude cpt-S 4.1 mb
Dell Latitude cpt-V 3.8 mb