Windows Vista blocks files from other computers?

[Thorin]

Today was one of those not fun days where I lost literally hours and hours trying to overcome file blocking issues in Vista. [...]

As part of our courseware development we use an internal tool that allows us to review course content. This tool uses an embedded IE browser for preview. The files that are opened in the browser are HTML pages that include references to JS files and .HTC files. Today I installed this tool on Vista and then copied the generic course template files down from our courseware SharePoint site. As I ran the course for the first time, I got [an error] message. [...]

I then went via explorer to find the file that it was attempting to open and I noticed in the property window "This file came from another computer and might be blocked to help protect this computer".

source: http://blogs.msdn.com/gblock/archive/2006/12/19/tips-steams-zones-vista-and-blocked-files-in-ie.aspx

Apparently, Windows XP Service Pack 2 and Windows Vista will tag files that come from anywhere other than the local computer and Vista will actually not allow you to use the file until you've unblocked it.  Uhh...  I don't think the average user is going to find this particularly intuitive...