Media: DVD-R for backups, not DVD+R.
Due to uncertain / unconfirmed factors, the Wii will read DVD-R media better than DVD+R. Please use DVD–R media when recording discs intended for the console.
My personal theory …
The Wii’s DVD-Rom has drive chips on it labeled “Panasonic”. Also, the only brand of PC drive to read a Wii disc is made by LG. I believe that the Wii DVD drive is manufactured by Nintendo using a combination of LG and Panasonic parts.
In 1995, Panasonic, LG, and other major electronics corporations founded The DVD Forum. The DVD Forum is an international organization composed of hardware, software, media and content companies that use and develop the DVD and HD DVD formats. Most importantly, the DVD Forum created the DVD-R and its standards.
In 1997, Sony and other corporations founded the DVD+RW Alliance. In 2003, Microsoft officially backed the DVD+R format.
When a retail game is created, it’s factory pressed, therefore neither –R or +R in nature. It would only make sense that the hardware behind the Wii, LG / Panasonic with 14 years of DVD-R experience, would recognize the –R standard better due to its association / history / founding of the format.
Either way …
After spending much time on WiiHacks.com, I’ve come to witness many issues being resolved by DVD-R media. The other staff can vouch for this statement also. To minimize errors, please use the –R media when recording discs intended for the Wii.