An old IE bug has struck again. Many versions of Internet Explorer have trouble downloading files over SSL (via an https connection). When you try to download a file from Web-CAT using IE, you may get an error indicating it is "unable to download", and that the requested site is unavailable. This is due to a bug in IE, which does not correctly download these files because it believes it should not store a copy in its local cache. As a work-around, you can simply go to your browser's address bar and change the "https:" at the beginning of your page address to "http:" and reload the page. You'll turn off SSL, and IE should then be able to download the file.

To read more, look at this Microsoft knowledge base article (actually, there are several that are relevant). Note that the problem also appears in newer versions of IE than those listed in this article--it has been "fixed" and has reappeared in IE several times.

There are three other alternatives you can use. First, if you want to try the basic options supported by Internet Explorer, choose the "Internet Options..." command from the Tools menu in IE. Click the "Advanced" tab. Scroll down to the Security option section and uncheck "Do not save encrypted pages to disk". This turns on cache support for pages/files delivered over SSL. This may do the trick, depending on the IE version you are using.

Second, if that doesn't work and you want to change IE's internal settings, you can download this registry file: ie-bug-fix.reg. Save it to your local machine. Then right-click on it and "Merge" or "Install" it. It is a plain text file, so you can look inside--it adds a few registry keys, based on various MS knowledgebase articles. These changes tell IE to ignore any cache control headers from SSL-based URLs and to always allow caching of downloaded files. This will fix the problem.

Alternatively, you can disable SSL in your connection to Web-CAT. You can do that just by logging in using a non-SSL URL. At the VT web server, you can login using this URL to disable SSL for your session: http://web-cat.cs.vt.edu/Web-CAT/WebObjects/Web-CAT.woa.