He is not the only one. I also live in Europe and just bought a new computer as my trusty old Windows 7 machine from the US had slowed to a crawl, and Turbotax refused to work on it. Rather than attempt to upgrade the old machine to Windows 10, I got a new one. Guess what. German kezboard layout, etc etc.
But bizarrely Turbotax was ok till I started messing with the regional settings. I never connected the problem to that till reading this thread. I changed everything I could find in settings to US formats and now TTX is happy.
I agree it is definitely a bug. Number should not increase by a couple orders of magnitude when you hit return, no matter what. I agree with the suggestion that for TTX, it should insist that whatever is typed in is in US (IRS acceptable) format. Anything else should produce an error message. And never should a number self multiply by a 100 when the user hits return!
