sounds like a BIOS resource/IRQ conflict ( this will mostly happen after a reinstall or crash after adding new hardware to the system )

 

basically, get into your bios, and load the defaults, and turn off your IRDA port, and serial ports ( just for now ) then start windows back up, and update the driver, if it still locks try disabling other hardware thats in the system.

 

if all fails, you will have to contact dell, due to a motherboard failure ( yes this is common too, espically on a 3-4year old system ).

 

but try what i said and give us updates.

I had already called dell support before I saw your message and they thought it was the motherboard, so they sent out a technician and replaced the motherboard and that seems to have fixed it.