I have been having the same problem with my Inspiron 531 and was wondering if you ever found out what caused it. Mine freezes up and diagonal lines appear across the screen. Thanks.
I am having a similar problem with my less than a week old XPS 8300 and have had some conversation about it here:
I also here the Aurora's are having similar issues:
And the Optiplex also:
What is going on with the Dell desktops?!?
XPS 8300, SNB, i7-2600 (3.4GHz) | SDRAM - 6GB DDR3 1333MHz | Optical drive - 16x DVD-RW | Video - ATI Radeon HD 5670 1GB GDDR5 | Monitor - Dell U2311H 23IN FP | HDD - 1TB SATA 2, 7200 RPM | OS - Windows 7 Ultimate SP1 64-bit | Audio - Creative Labs SB X-Fi Titanium PCIe
Latitude E5420, Intel(R) Core(TM) i7-2620M CPU @ 2.70 GHz | 8 GB RAM | OS - Windows 7 Ultimate SP1 64-bit |