Adobe’s products have received recent scrutiny from the security community. In fact, many have suggested that their products will be the main target for malware in 2010. Why? Well Adobe’s Acrobat Reader and Shockwave are very widely distributed and many vulnerabilities are being discovered which often remain unpatched for a while. Adobe has some improving to do.
In the meantime, you can protect yourself somewhat and still use Acrobat Reader. These steps do not guarantee your safety but do reduce your risk profile.