Thank you for responding. My machine is an Acer e machine, model E1352. Windows 7 came with the computer. I've had it 7 months. The only things I have plugged in are the mouse,speakers,monitor,canon printer, modem & keyboard.
My trouble started when I decided to uninstall a program I actually paid for, called Tune Up Utilities 2012. I didn't like it at all. I used to have the 2008 version and like that much better. I think that's when my trouble started because I uninstalled it via Revo Uninstaller, and there were over 1000 files so took me ages to tick them all. I should have uninstalled it via control panel. I don't like windows 7, in XP when one clicks all programs usually there is an uninstall option next to programs, not in win7. I have a feeling it was uninstalling other utilities if there are any in win 7.
Then to make matters worse I decided to install NTI CD & DVD Maker that came with my XP machine. I didn't look on the disk until after I installed it and says for win 95 to XP. Thats when my problems started with my DVD drive, when I tried to open NTI, Nero seemed to be mixed up in the whole thing so I uninstalled that as I had no choice because it had started. I didn't even know Nero was on this machine, I've never used it cause I don't like it, don't understand it more like it. I found an entry "somewhere" in this computer that said "Nero' so I clicked on it and reinstalled Nero. I think my DVD drive is working now. When I uninstalled NTI I looked in recycle bin and one of the icons said "engine" and I deleted the bin anyway. I have a feeling that "unknown device", has something to do with the DVD optical drive. Every now and then a message pops up that a driver is not installed......so don't know what to do now. The DVD drive seems to be working now but I'm concerned about the entry "unknown device". I had promised myself I wasn't going to mess around with this machine like I did with my XP desktop. I had to format and reinstall Windows on that and now I have given to my friend. I still have a laptop with XP on it.
Sorry for all the information but thought I better tell you.