As Barry noted, this error has been around for some time. There are at least a couple of things that cause it (like content larger than space on disk, PD9 burn speed set to DVD maximum.which is higher than media capability, etc.) however, I have a few things you should attend to, that might help:
1. Something is wrong with your DVD drivers in Windows 7. Drivers should NEVER be "0 bytes". This is from your DXDIAG:
Model: PIONEER DVD-RW DVR-216 ATA Device
Driver: c:\windows\system32\drivers\cdrom.sys, 6.01.7600.16385 (English), , 0 bytes
You can try using DEVICE MANAGER to uninstall, then scan for hardware changes to see if it finds a good driver. Or install Service Pack 1 for Windows 7.
2. Please update your Video Drivers. Many things related to PD9 are affected by the driver version (yes...even burning). Get the current WHQL release 275.33.. but be aware a new one is due soon, so go back in a week and look for another one:
3. Are you running the latest PD9 build ? Click on the word POWERDIRECTOR in the upper right of the program (My build is PowerDirector Ultra64 126.96.36.19930). If not, click on "downloads, software updates" from the menu at the top of this page.