Yes there is a limit to how many times you can rewrite a CD or DVD RW disc. No, it's not a specific number like 10, or 20. It depends alot on the quality and the age of the disc.

Toshiba Brings World’s First Slim HD DVD Rewritable Drive to Mobile PCs; New HD DVD Rewrite Capabilities Turn Mobile PCs into Desktop Replacements with More Tools to Create High-Definition Content ...

Toshiba unveils at the Computex trade show its slim HD DVD rewriter, which the company will begin sampling to PC makers in July Toshiba will unveil in Taipei on Tuesday a slim HD DVD rewriter suitable ...

The ZL40510 and ZL40511 debut as the industry's first laser-diode drivers to support optical disk drives with x16 DVD and x52 CD write/rewrite speeds. According to the company, the drivers will allow ...