I'm testing with Safari 5 (and most all other browsers) running on XP.
Add to cart works fine. However, if I do not go to the cart and leave any product page connected with VM, the sidebar mini-cart says it is empty. If I return to a VM product page, the contents of the mini-cart reappear.
Moving to a category page and the contents seem to vanish. Going to a product page, the contents of the mini-cart reappear.
Trying to check out and the contents disappear.
Seeing how FF, Chrome, IE 6 through 8 and a couple others work fine on my various PCs running a couple different versions of Windows, I am led to believe it is something that Safari is doing as regards cookies, page caching, or ?
I just loaded Safari last night, so this playing with that browser is just that, playing. I have an email off to a friend who is a Mac developer and have asked him to look into this issue. I'll report back.
Take care, Mike
by the way, the site isn't ready for prime-time, but Kelvyn, perhaps my site would demonstrate the issue versus yours. If so, then it may be that my templates and or set up is causing or enhancing the issue.
http://beta.wenzloffandsons.com