went away
The problem is with motherboard (in my case, at least).
When a Dell technician came and changed it the problem went away. But before that they had changed my HDD and it wasn’t it.
I've got a 630i and the errors were exactly like those had been described before: I was getting the Blue screen (Memory_Management). The issue appeared the very day the computer was delivered. Never crashed while playing games. Would crash for sure if you were running AVG antivirus. I was getting "Superfetch stopped responding" and "Host Process for Windows Services has stopped working" errors (with flashing screen). Browsers tended to crash as well. I even installed a clean version of Windows 7 (with the same error message on the blue screen).
I’m sure that the problem is gone because it has been some time and the system hasn’t crashed a single time and the first thing I did was starting AVG Anti-Virus. Before they changed MCB it would crash the first five minutes running. Moreover, browsers stopped crashing and the screen doesn’t flash anymore.
The guy who bought their 630i on Ebay can either buy a new motherboard (provided that it works fine with other parts) or just ask dell to change motherboard (they’ll still do it if it’s not under warranty but it’ll cost you).
By the way, I bought mine (630i) in Australia.
On my630i*com/resources/driversandfirmware (replace * with . ) you can read the following (click on "New users: Click here for an important note regarding your 630i"):
"Both new and refurbished 630is from Dell can, and occasionally do, arrive with problems, so it's important to check it all out thoroughly. The reason for this is that you only have 21 days from your Sales Invoice date in which to return your system. If anything doesn't seem right, don't hesitate to (first of all) call Dell and notify them of the problem(s), and then also let us know. Unfortunately, some 630is are just lemons, meaning that no matter how much hardware is repeatedly replaced or swapped out, crashes will still happen. If this describes your situation, and you're still within the 21-day return period (U.S.A.) or the 7-day return period (U.K.) from the date of your Sales Invoice, it is highly recommended that you contact Dell and arrange to have your system returned or get a full monetary refund.
The key difference/benefit in returning a system as opposed to having parts constantly replaced is simply getting rid of a lemon. There have been a number of 630i users (my630i*com/resources/xps_630i_customer_experiences.html) whose systems were literally fraught with BSOD or other errors regardless of how many components were replaced...until they got a completely different 630i. Aside from poltergeists, no-one can explain how replacing all the components isn't successful, and a brand-new unit is--but it does work.
Brief system specification
Basic Hardware information
Motherboard: XPS 630i
Motherboard Vendor: NVIDIA
Motherboard Version: 2.0
Motherboard Model: NVK84CRB
System BIOS version/date: Dell Inc. 1.0.12, 10/28/2008
Basic I/O System(BIOS): Phoenix - AwardBIOS v6.00PG
Central Processing Unit(CPU): Intel(R) Core(TM)2 Quad CPU Q9300 @ 2.50GHz
Physical Memory X 4
512MB
512MB
1GB
1GB
Hard Disk X 2
WD My Book IEEE 1394 SBP2 Device (0.91TB)
ST350062 0AS SCSI Disk Device (465.76GB)
Video Card: NVIDIA GeForce 9800 GT
Monitor: Dell E248WFP(Digital)
Audio Device: Realtek High Definition Audio
Network Adapter
Local Area Connection - NVIDIA nForce 10/100/1000 Mbps Ethernet (Connected)
Keyboard: USB Input Device
Mouse: HID-compliant mouse
Hardware Score (Base score: 5.9)