DVD won't read & CD-R locks up when trying to install programs

Windows XP
Dell 4700 w/ Pentium 4 Processor 530 (3.0GHz)
Samsung DVD-ROM SD-616-E
Samsung CD-R/RW SW-252S

Installed Adobe Photoshop Elements 5.0 and got message some files were missing. Tried “repair” - same result. Uninstalled Photoshop. Rebooted and tried to install Photoshop again. The DVD won’t read the disc and the CD-R reads the disc, but locks up the computer half way thru the load. Tried a system restore, and that worked for a while, but now I’m back where I started, maybe worse, can’t get the either drive to read the CDs. Uninstalled all the drag & drop software & Sonic, rebooted, same result. The DVD player spins the CD a couple of times, but won’t recognize the disc. Anyone have any suggestions on how I can get the drives working again?