Photosynth Thinks my PC is a mac?

This could not be further from the truth. I'm on Windows Vista Ultimate with IE8 (IE7 emulation mode). I've since removed IE8 but am still getting this.

This also effects me with viewing select Silverlight 2.0 content (such as the NBC Olympics video). Why is my computer saying it's something it's not?

I have the same problem when connecting my Laptop trought my cell phone (wich uses vodafone's proxy). When on Wifi/LAN at home it works perfectly.

I saw this happen for a while with my combination of FireFox and IE tab. My Windows Live login was set to use IE tab, while most of the time I use regular FireFox. As soon as I forced the browser to always use FireFox, it stopped complaining that I was using a Mac.

To make that experience useful for other users on other setups: my guess is this has something to do with the exact browser version you are using, and the information your browser/internet connection provides to the photosynth site. Try a different browser, try a different connection.

(In any case, it's a bug. You're not using a Mac and photosynth should be a bit more humble about its opinions :) )

Obviously. Since Photosynth has the capability to view anything from all angles, it feels your PC is Mac

Any news ?

Sounds like something is messing with your HTTP_USER_AGENT header. What does this site say when you visit it?
http://whatsmyuseragent.com/

If you've installed some kind of plugin that has messed it up then photosynth.net might detect it incorrectly and think you're on a Mac. If you can post your user agent string here then people can test this with a user-agent switcher program to see if its the problem

I'm using Firefox and mine says:

Your User Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-GB; rv:1.9.0.1) Gecko/2008070208 Firefox/3.0.1

PS thinks this is Mac:
Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0; MRA 5.1 (build 02243); SLCC1; .NET CLR 2.0.50727; Media Center PC 5.0; Tablet PC 2.0; .NET CLR 3.5.21022; .NET CLR 1.1.4322; .NET CLR 3.5.30428; .NET CLR 3.5.30729; .NET CLR 3.0.30618; OfficeLiveConnector.1.2)

Found the bug and can reproduce it.
If the user agent string in the browser is too long then the website detects you as a mac.

I will repost this with full details as a bug report, then post a link here. I'm guessing that's the proper way to do things anyway :-)

edit: bug report

Your two options are-
1) Get Firefox and use that for viewing the website until MS fix the problem. this is the safe option
2) Export the pictured registry key, then delete some of the rows from it. This may break other websites or even your browser! You can import it again to fix the problem, or use a system restore point DON'T DO THIS IF YOU DON'T KNOW WHAT YOU'RE DOING!