Adobe has tested Acrobat 9.x (Standard, Pro, and Pro Extended) on Microsoft Windows 64-bit operating systems. Acrobat 9 is a 32-bit application that was tested on Windows Vista x64, Windows XP x64, and Windows 2003 Server x64. Microsoft Windows 7 Starter, Home Premium, Professional or Ultimate or Enterprise 64-bit is supported after the 9.2 update has been applied.
A known issue in Windows 64-bit operating systems affects 32-bit printing applications running in these 64-bit environments. This issue affects the Adobe PDF printer.