Knowledge Base Article: KB53 - Created On: Jun 18, 2009 12:50 PM - Last Modified: May 2, 2012 06:23 AM
You need the last available update to Version 3 for Vista or Windows 64 bit versions here.
KB#274: I have a problem with installing v.3 PDF-XChange on my new computer.
KB#281: How do I Tell if my Windows is 32 or 64 bit?
KB#37: How do I determine what SDK product I need?
KB#46: How do I post a support request to the forum
KB#54: How do I upgrade my existing product to another product?