W7 upgrade always stops at Completing Installation

[Grimmbro]

I am continually running into the same problem as I try to upgrade to W7. Once the installation is nearly completed (using a family pack W7 upgrade DVD to upgrade XP P2) the PC reboots as it should and returns to the completing installation step where it lingers for a a short while and then the screen displays a small message from my monitor to tell me that the Digital signal has been lost and the screen goes blank. When I try to reboot it repeatedly ends on that same place. Does anyone have any idea why it would do that. Advice is welcome and appreciated.

[glc]

What ports do you have on your video card and what are you using for a monitor?

[Grimmbro]

My monitor is a Viewsonic VG2030wm monitor.
Newegg.com - ViewSonic Graphic Series VG2030WM Black 20" 5ms Widescreen LCD Monitor 300 cd/m2 800:1 Built-in Speakers

My video card (HIS H485QT512P Radeon HD 4850 512MB 256-bit GDDR3 PCI Express 2.0 x16 HDCP Ready CrossFireX Support IceQ4 Turbo Video Card )
has the following ports:
1 x HDMI (via Adapter)
2 x DVI
HDTV / S-Video Out
Newegg.com - HIS H485QT512P Radeon HD 4850 512MB 256-bit GDDR3 PCI Express 2.0 x16 HDCP Ready CrossFireX Support IceQ4 Turbo Video Card

[glc]

Have you tried the other DVI port?

[EzyStvy]

When you get to the blank part - have you let it sit 5 to 10 minutes?

[Grimmbro]

I will try the other DVI port later this evening when I get home. As far as letting the PC sit and wait for 5 -10 min, I have done so and it will usually reboot after the first try and end up at the same place with the screen going dark and if I leave it sitting for an extended period after that, it just sits there and does nothing.
Also, at this point when I try to boot up from the hard drive it gets to the initial W7 screen and then the monitor signal dies and it just sits.
By the way, I tried installing thye 32bit version and had the same results.

[Grimmbro]

Well, I tried connecting the monitor to the second DVI port and it made no difference. I also, booted from the upgrade disc and stopped at the point where it allows you to load drivers and I loaded the monitor drivers but it did not make a difference. I am going to restart the whole process, format the hard drive using the XP installation disc and then I will run the scan for malicious viruses or malware. There is a note along the way when installing W7 that says that this could be causing problems for some upgrades. So with that in mind I am hoping for some better results.
Just wondering whether the entire hard drive needs to be formatted to successfully install the upgrade or is it enough to have the target partition only formatted. I was planning to format the rest of it later after successful OS installation. After all, it is 1.5 tb so that could take a while. As you can see I am trolling for any kind of possibility that would be causing this issue.

[Grimmbro]

THE BEST NEWS EVER !!!
I have successfully loaded Windows 7 64bit onto my rig. After two miserable months of trial and error I was able to do this after removing the existing video card I had and replacing it with a less expensive and less extravagant video card. Therefore, if anyone experiences the same issue I have described, switch video cards and see if that may be the problem. I do know that there were no driver issues with the video card when running XP all the way to SP3 with current updates. But it did have some sort of issue with the W7 installation process. Thanks to all that offered help and suggestions, I really appreciate it.