You haven't provided enough information.
Which Dell Dimension model is it ?
Did the subject burner drive come with the Dimension ?
CD-RW - ONLY - drives can't read a DVD of any type.
- you may be calling a drive a CD-RW drive by mistake.
- your ScanSnap scanner more likely came with a CD-rom disk, NOT a DVD-rom disk - if that's so, any optical drive should be able to read it, if there's nothing wrong with the drive or it's connection.
Older Dimension models may have come with a CD burner (only) drive, or a DVD-rom / CD-rom drive, or a combo CD burner / DVD-rom drive. Newer models would have a combo DVD burner drive - reads and burns both CDs and DVDs.
If it didn't come with the computer, how old is the burner drive ?
Optical drives DO NOT work perfectly forever.
Does it read other CDs and DVDs fine ?
If you DO have a combo DVD burner drive - reads and burns both CDs and DVDS - DVD burner drives have at least two lasers and associated circuits. Sometimes one of them malfunctions after the drive has been used a lot.
Does it read ONLY CDs but NO DVDs,
or - does it read other DVDs but NO CDs ?
If the burner drive is not new or fairly recent, have you tried using a laser lens cleaning CD in the subject drive ?
If you don't have one, you SHOULD have one. Most places that sell CDs and/or DVDs have them, or at least some "dollar" stores often have them for a buck or two.
Have you installed Windows from scratch and it's only after you did that, that the DVD burner drive does not recognize some disks ?
Fujitsu makes ScanSnap scanners, NOT Snap Scan scanners.
Which country did you buy the scanner in ?
Which ScanSnap model is it ?
Searching on the web with ScanSnap finds that...
The disk that came with your ScanSnap scanner, the one with the software on it for the scanner itself if it came with more than one, is more likely a CD-rom disk, not a DVD-rom disk.
DVD burner drives can read and burn CD disks as well as DVDs, if there's nothing wrong with the drive or it's connection, except possibly DVD-RAM burnable disks, which would not be what the software for the scanner would be supplied on.
If it's on a DVD disk, is it a copy of the original disk ?