I actually noticed this "problem" yesterday. I was watching a DVD on my PC and when I looked at the CPU box, I noticed the HD light constantly flickering. My HD is a Maxtor 7200RPM 80GB unit. I checked out my processes, and I had no virus scanning in the background. Hard drive stopped when I stopped the movie, and when I started it again, the hard drive lighted started flickering again. Why does the HD have to work when a DVD is on? I thought that DVDs had nothing to do with the Hard drive. Is this normal?

this is likely normal. your HD and DVD are different drives, but they are both connected to the same PC running the same OS. DVD drives are MUCH slower than hard disks. Most DVD player software buffer large amounts of data in memory or on HD first so that they can display the move smoothly.

Well, I don't play DVDs on Windows, but when I play DVDs (Linux), I don't have this problem. However, I do notice that a significant portion of my physical memory (640 Meg) is being utilized. I don't know how much of your memory is being used before attempting to play a DVD, but maybe you are having to do some swapping (virtual memory) or there's a setting in your DVD player software that tells it to cache itself in memory or to disk. With 512 meg of memory, it seems unnecessary and unfortunate that it's reading/writing from your hard disk during the playback of a DVD. So, is it normal? Maybe. But, I do not believe it should be.

Years ago you'd find hardware decoder cards in a PC (my laptop has one). This is now done with software which lives on your hard drive. If you didn't have the software on your computer your hard drive wouldn't be doing this but you likely couldn't watch the movie either. That DVD has a helluva lot of video and audio information and it all has to be decoded and processed before it hits your monitor.

SkipCox, I agree that years ago you'd find hardware decoder cards for DVD drives in a PC (I've never personally had such a card) However, I know that the software now required to play a DVD doesn't add up to hundreds of megabytes of code. I do believe that the software may utilize a large amount of buffer area (possible hundreds of megs) to play audio/video, but I certainly don't want my system to be constantly reading/writing to disk for hours while I watch a DVD. I guess that Windows XP is such a memory hog that there's not enough room for this buffer area to exist in physical memory, even with 512 Meg of memory! What a poor and unfortunate design. This just gives me another reason not to go with XP. Even when I was playing DVDs on my K6/2 with 256 Meg of RAM, I didn't have the problem he speaks of, in Windows 95 or in Linux.

Guys, I popped a dvd in my machine and although I could see the cpu doing some work, it wasn't steady. This is with a Duron1300, 512Mb 133 sdram and 512Mb swap file. In a quick effort to use another application I could certainly tell I had something big running. Looks like I need to do some more research on this to see what makes it tick.

Thanks for the replies. Maybe the hard drive will calm down when I upgrade to 1GB of RAM. After all, the activity lessoned when I went from 256 to 512MB. So thanks and happy computing!