I couldn't get in this morning, but I thought it was my server at work. I tried again just now and couldn't get in. The proxy server timed out. The network here is slow, but I can get just about everywhere else without a problem.
I am able to reach www.kubota.com without any problem. Maybe you could clear out your browser cache, or just re-boot, and see if you have success.
Sometimes sites (including this one) go down for brief periods due to maintainance or simply extreme Net loads. But I do not think there is any problem with the Kubota website.