Problems with DVD burning for back-up

[DDiego1000]

Hi,

I'm having trouble backing up some data such as .m4v, disk images, dvd movies on with my dvd burner using blank dvd-r media. Whenever I burn a dvd with any of the files above, it all works fine until I eject the burned DVD-R.

I used the Apple burn command under file. Before I eject the dvd-r after burning, I test the files burned in the dvd if they can be opened by the appropriate application. I also verified the dvd by using the disk utility and it said it appears to be OK. After I eject it and re-insert it in the dvd drive, the drive ejects it after a few second. I also tried resetting PRAM--turned off computer, held Option+Cmd+P+R before the grey screen comes up, hears the start-up sound, then I let go of the keys for the computer to turn on.

The media I've been using is RIDATA (Ritek) DVD-R, 4.7 GB, 120 min.


Here are my hardware specs:

HARDWARE OVERVIEW:

Model Name: iMac
Model Identifier: PowerMac6,1
Processor Name: PowerPC G4 (3.3)
Processor Speed: 1.25 GHz
Number Of CPUs: 1
L2 Cache (per CPU): 256 KB
Memory: 768 MB
Bus Speed: 167 MHz
Boot ROM Version: 4.6.8f4


ATA SPECS:

ATA Bus:
PIONEER DVD-RW DVR-106D:
Model: PIONEER DVD-RW DVR-106D
Revision: A606
Removable Media: Yes
Detachable Drive: No
BSD Name: disk1
Protocol: ATAPI
Unit Number: 0
Socket Type: Internal
Low Power Polling: No
Power Off: No
Mac OS 9 Drivers: No
Partition Map Type: Unknown
S.M.A.R.T. status: Not Supported

ATA Bus:
WDC WD800BB-98JHC0:
Capacity: 74.53 GB
Revision: 05.01C05
Removable Media: No
Detachable Drive: No
BSD Name: disk0
Protocol: ATA
Unit Number: 0
Socket Type: Internal
Low Power Polling: No
Mac OS 9 Drivers: No
Partition Map Type: APM (Apple Partition Map)
S.M.A.R.T. status:Verified

Volumes:
Hard Disk:
Capacity: 74.41 GB
Available: 2.29 GB
Writable: Yes
File System: Journaled HFS+
BSD Name: disk0s3
Mount Point: /


DISC BURNING SPECS

PIONEER DVD-RW DVR-106D:
Firmware Revision: A606
Interconnect: ATAPI
Burn Support: Yes (Apple Shipping Drive)
Cache: 2000 KB
Reads DVD: Yes
CD-Write: -R, -RW
DVD-Write: -R, -RW, +R, +RW
Write Strategies: CD-TAO, CD-SAO, CD-Raw, DVD-DAO

Also I'm currently using OSX 10.5.7

Please help!
DDiego1000