Q: I have a Dell Dimension 9100 tower PC with Windows XP Media Center Edition. Last week I noticed my monitor was black when I powered it up in the morning, even though I could hear everything booting up over the speakers. Only by powering it off and on manually with the tower button would the video reappear. This problem only seems to occur after the PC has been off overnight. Restarting it during the day was not a problem.

My PC is under Dell warranty. Repeated calls to tech support have not solved the issue. Tech support has changed video drivers and disabled my USB ports at boot-up (thinking my PC was trying to boot from my external HD backup). They told me if the video card was bad I would not hear anything from the speakers. I’ve checked my monitor cable connections to my tower.

Can you suggest a solution?

— Gregg Taylor, Mercer Island

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A: I’d put my money on the graphics adapter — either the driver or the hardware itself — as the culprit. It seems that the graphics adapter is not reawakening when your computer wakes up from sleep mode.

Sound and graphics are generally not, by the way, handled by the same hardware, so the fact that you have sound doesn’t let the graphics adapter off the hook. And, in any case, the only thing you should hear over the speakers during bootup is the Windows startup tune.

Finally, it’s not likely to be the monitor, since apparently a cold reboot brings your video back.

Because your computer is under warranty I’d ask for a supervisor in tech support and tell him or her that the troubleshooting procedures have failed to resolve the issue and Dell needs to fix the problem. If you get tired of dealing with tech support, you can quickly narrow down the problem by trying a different monitor with your computer. If the problem doesn’t disappear, it’s time to try a different graphics adapter.

Q: I have Windows 98 but my computer informs me the hard drive is full. Is it possible to add a slave drive with XP?

— Albert Sharpless

A: Absolutely. There are three things to keep in mind. First, if you want to keep costs and hassle to a minimum, you’ll want to buy a drive that is the same type as your primary drive. That way you can probably just attach it to the same cable the primary drive is plugged in to and you won’t have to install a new controller card.

Second, you may need to make changes in your computer’s BIOS so that the computer knows that second drive is there. Consult the user manual that came with your computer for specific directions.

Finally, depending upon the drives you’re using you may also need to set jumpers on the drives to specify that one is a master drive and the other is a secondary drive.

Q: My Compaq Presario R3000 running Windows XP has suddenly stopped playing AVI files. There is sound but no image. There is also no image in their thumbnails. I have tried searching online for help and the best thing I have found is to download codecs. I have already done that, downloading both GSpot and Divx codecs. It was working fine, and now it isn’t. Any ideas?

— Joe Campbell

A: There are two things to consider. The first, as you suspected, is whether you have the appropriate codec, which is essentially a little program for converting the analog signal into a compressed digital format and back again. If you don’t have the right codec for that file, you can’t play it back. I’d suggest you try downloading an AVI codec pack and see if your problem goes away. You can find a variety of free codec packs on the Internet.

The second potential cause of your problem is your graphics adapter. Did you recently change the configuration of the graphics card or install a new driver?

Questions for Patrick Marshall may be sent by e-mail to pmarshall@seattletimes.com or pgmarshall@pgmarshall.net, or by mail at Q&A/Technology, The Seattle Times, P.O. Box 70, Seattle, WA 98111. More columns at www.seattletimes.com/