I have been having the same problem with my new XPS 8300. This started happening the same day that I unpacked it out of the shipping box at the end of April/beginning of May (can't remember when I actually received the box.. After hours on the phone and trying different solutions I gave up and requested a replacement desktop. Still waiting for it to be shipped.
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 |