ASP.NET MVC site having problems with MACs

We have a site at: http://www.racedayworld.com which was built using ASP.NET MVC

There are currently a couple people who cannot use the login form when using a Safari on the MAC. The problem is a strange one as I (the developer) have a MAC and can login just fine with Safari. What happens is they put in their credentials and the site just reloads, but doesn't log them in...

I'm including 2 examples of the support details we collected from them to see if there was any common problems..

• Operating System Apple Mac OS X 10.6.4 Intel
• Screen Resolution 1280 x 800
• Web Browser Safari 5.0.2
• Browser Size 1190 x 690
• Color Depth 24 bit
• Javascript Yes
• Flash Version 10 (10.0.45)
• Cookies Yes
• User AgentMozilla/5.0 (Macintosh; U; Intel Mac OS X 10_6_4; en-us) AppleWebKit/533.18.1 (KHTML, like Gecko) Version/5.0.2 Safari/533.18.5

• Operating System Apple Mac OS X 10.5.8 Intel
• Screen Resolution 1440 x 900
• Web Browser Safari 5.0
• Browser Size 1440 x 776
• Color Depth 24 bit
• Javascript Yes
• Flash Version 10 (10.0.45)
• Cookies Yes
• User Agent Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10_5_8; en-us) AppleWebKit/533.16 (KHTML, like Gecko) Version/5.0 Safari/533.16

Sounds like a cookie issue to me

I've seen a very similar error before with MVC & Safari & logging in. Try checking the log files in C:\Windows\System32\LogFiles\HTTPERR and see if there are any 400 server errors. Have you also checked main event viewer logs for any server errors?