Mac OS X v10.6: About incompatible software
http://support.apple.com/kb/HT3258

Mac OS X v10.6 Snow Leopard is designed to protect your Mac from certain incompatible software that can quit unexpectedly or cause other issues in Mac OS X v10.6. When you install Snow Leopard or migrate to Snow Leopard, known-incompatible software is moved to a folder named Incompatible Software on your hard drive. Snow Leopard also prevents known-incompatible software from opening. If you see an "Incompatible software" message, contact the software's vendor or visit their website for a later, compatible version.

"During installation, Snow Leopard moves known-incompatible software to a folder named Incompatible Software at the root level of the hard drive. If you see this folder on your Mac, use the table below to check with the software vendor to see if any Mac OS X v10.6 Snow Leopard-compatible updates are available."

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