Seems like some sections and downloads are not available the the Garmin Developer SDK area. For example I cannot download the SDK for windows. I cannot go to the "User Interface" section of the "Programmers Guide", some parts work other don't. I receive "504 -Gateway Timeout" when trying the get/reach these resources. It has been like this for at least a couple of days, any one else experiencing this?, I have tried to get in contact with Garmin about this but haven't got any response.
Like Hermo, I'm not having a problem with the developer site. Have you tried a different browser and/or machine? But like Hermo said, if you can get the SDK, you will also have the latest Programmer's Guide on your machine (the second item in the menu he posted)