Boot problem - missing files?

I am concerned about my machine which is running XP SP1. Sometimes when it boots I get a message that it can not find a dll or that something is wrong with one of the windows system files. Today it started to boot, got opening screen and then it went black, no more booting.
When I turn it off by holding in the power button, try to reboot again, eventually it boots up. But I am concerned that one of these times it will not boot. Anybody have any idea what my problem is?

 

If you get the black screen again, check if there is still HDD (LED) activity. Also (after HDD activity has stopped), do CTRL-ALT-DEL -> ALT-S -> Enter. If that shuts the machine down, then there is a problem with the graphics drivers (unless there may be a problem with the graphics hardware itself). Go to Safe Mode. If it seems stable there then go to Control Panel -> Add/Remove Programs and remove the listings for ATI. When you reboot Windows will ask for the drivers for the graphics. If you don't have the graphics drivers on CD (they could be on the motherboard/chipset drivers CD if the graphics are built into the motherboard), cancel out of the hardware drivers wizard and run the ATI drivers installation program in Windows. Only install the basic items if you can.

Matt

 

The bootup would start with the HP intro screen and then a count down if you had a dual boot and then a black screen. The HD light was either out or a steady lit but you could hear there was no activity on the HD. It was silent and the booting had stopped. I ran "sfc /scannow" to check all the windows loaded files.
Do you know if there is a parameter, or log, with this scan that will indicate whether any files were corrupted or replaced?
I am on the computer now, and after the sfc it booted up normally. I don't think it is a video problem because the booting stopped when the screen went black.

 

When I look at the event viewer I see when the scan starts and ends and there is no info between these two lines.
However I do find a couple of Red X's with the following comments:
REDX1. The nVidia WDM Capture (universal) service failed to start due to the following error:
The service can not be started, either because it is disabled or because it has no enabled devices associated with it.
RedX2. The nVidia WDM A/V Crossbar service failed to start due to the following error. The service can not be started, either because it is disabled or because it has no enabled devbices associated with it.
I notice when I shut down my computer I get an error message that Dr. Watson is trying to check something or other or to close.
The RedX's occur everytime I boot my computer. Do you have any idea what this is all about and how I can prevent the redX's from occurring?
Thanks for your help.