Bought originally 10.1 version , then downloaded update since I am using Panther now. FAXstf X 10.5 constantly crashes, or cuts incoming faxes off in the middle. Called customer service (no 800 number - 20 min hold time) - a very unfriendly customer "service" agent explained that since I didn't buy FAXstf X for Panther, but downloaded the update, I do not qualify for customer support.I use a lot of different software products for OS X, but this is the most problematic product with the worst customer service I have ever experienced.Well done - SmithMicro!PS: Buy PageSender from SmileOnMyMac instead: half the money for a much, much better product (http://www.pagesender.com)