This will occur if you click on a link to a .pdc or .llv file in Internet Explorer before you have installed the secure viewer software. Mozilla Firefox correctly identifies the file as binary and asks if you want to download it.
If you have installed the Viewer software then it could be that your registry settings were not updated correctly to associate the file types with the Safeguard Viewer software. This may be because you did not install the Viewer software as a Windows Administrator.
If you download your license file using Safari, then Safari may add a .txt file extension to it (for example, license.llv.txt) and then open it with the default editor. You must close the editor, then remove the .txt extension before double-clicking on the license file to register.
If you download your license file multiple times, then Safari will add both a number and a .txt file extension to it (for example, license.llv-2.txt). You must remove all text after the .llv file extension before double-clicking on the license file to register.
If you are a publisher and want users to be able to download .pdc or .llv files before they have installed the viewer software then you need to register the PDC/LLV mime type on your server.
You must also register the MIME type if you are using a Windows IIS server.
Another solution would be to use a file download script that would serve the PDC/LLV files with the correct MIME type. For example, Zubrag Smart File Downloader. Not only does such a script prevent the IE problem, but it will also prevents IE security alerts for file downloads. Smart File Downloader is freely available, and can also be used to avoid direct files downloads (hide real file paths), to limit downloads to only some set of file types, and to log downloads.