Support.Dell.com

So thats what was causing the problem with my system. I was having quite a few networking problems. I was blaming my ISP service. So whenever this type problem occur I quess you would have to flash the BIOS with the 2.5.1 version. Will that do any damage to the motherboard and what about performance. How will going back to the previous BIOS affect my system? And then just today or early this morning Microsoft came out with a stability update that also addresses software registration. Having my UAC turned off one of the updates that I don't currently have the ID with me would not or will not install unless you enable the UAC option. Then it will install properly like the other 3 updates. I don't mean to bombard you with questions but I consantly check the BIOS updates because it seems as though DELL has one every month. Therefore I kept seeing the old BIOS version 2.5.1, so I figure it was just a mistake. I appreciate the headsup.

From the XPS Site:

 

Note on the BIOS:  Dell told me that the 2.5.2 was pulled a few days after release because in some cases it was damaging internet network abilities and preventing internet access on some systems.

Just go back to the Dell site and flash back to the old Bios.  My understanding it should not effect your system.