After installing vista service pack 1 my dvd rom is gone.

try these drivers

http://laptop-problem.blogspot.in/2012/01/acer-aspire-5315-windows-xp-driver.html

If it truly needs a driver then install patin-couffin It will bypass all that windows uses now and accurately talk between drives and the dvd-rom. But it sounds to me that your dvd-rom just failed. You never know when they are going to go

Please give me the exact model....Turn the laptop upside-down and read carefully the label...

Operating System Windows XP Professional with Service Pack 2
Windows XP Home with Service Pack 2
Windows Vista Home Premium
Windows Vista Home Basic
Windows Vista Starter

1. Before upgrading to windows 7, you must check the specification of your acer aspire 5315.

2. Windows 7 is better than windows vista but if you are really wanted those acer programs to work. You have to downgrade your operating system from your previous operating system.

Ubuntu may not have the correct DVD criver for your computer. Since you hav gone back to XP you should go to www.acer.com and download the correct drivers for your model/serial no.

Access: http://www.acer.com/worldwide/selection.html
Select USA
Click GO
Click Service & Support
Click Driver Download
Click Notebook
Click Aspire
Click Aspire 5570Z
Click Confirm
Select the driver(s) -- they should be on the "original" CD-ROMs that were factory-shipped with your computer.

Try uninstalling the device and re-installing it, this should clear it up. Also you might want to seek out an updated driver.

You need to install the network driver.
Go to the ASUS WEB site to download the network driver for your computer. Download the Windows XP make sure it is for your model computer.

http://support.asus.com/download/download.aspx?SLanguage=en-us

I would try stopping the device and restarting it first.

If that doesn't work, find the latest drivers for it, and have them in a folder you can find easily. In device manager, you can right click, go into properties for the DVD-ROM. Click the update drivers button, and point it to that directory.

If neither of those work ,try completely uninstalling it from device manager, then going through the add new hardware option in control panel.

Please access the link given below. This link talks about a problem in the operating system.

http://support.microsoft.com/kb/q270008/

Let me know if your problem does not get resolved with this.

Thanks