So, you've tried changing the file type to a zip, and attempted to open it? How did you try to open it? With MSE, or with the native tool for handling zip archives that's built into Windows? You should not be using MSE to open it after changing it to a zip.
I generally use WinRAR for .zip and .rar archives. I find that it has more utility than the native tool on Windows. That being said, I've tried using both WinRAR and the native Windows tool, and the results have been the same each time.
My process has been as follows:
1. Download the archive.
2. Open the archive using WinRAR (or the the native Windows tool).
3. Double-click on the installer file.
4. When I double-click the installer, Windows prompts me to select a program with which to open the file. I'm thinking that the installer should just run when I double-click it, but it doesn't. I've tried selecting MSE at the Windows prompt, but all that does is open MSE. It doesn't install anything. I've tried fooling around and selecting various other programs to open the installer, but no dice.
5. Having failed to get the installer to run, I've copied it to my data folder and changed the file extension to .zip. Then I try double-clicking again, which would open it with WinRAR if it were an actual archive. But I just get an error message, saying that the archive is in an unknown format or is damaged. Then I try right-clicking on the .zip file and selecting "extract," but I get another error message saying that no archive was found. Then I try right-clicking and selecting "open with..." and using first Windows Explorer and then WinRAR, but both say that they're unable to open it.
6. Next I try changing the installer file's extension to .mse-installer. This hasn't worked for me, either.
7. Next I try changing the installer's extension to .exe and double-clicking. This brings up an error message saying that the software isn't compatible with my version of Windows.
8. I've also tried copying and pasting each of the folders in the archive to my MSE data folder, in the hopes that they would just magically appear in the program without my running the installer. Obviously, this hasn't worked.
If you've been trying to use the zip tool built into Windows and getting that message, there is something wrong with your download. If that is the case, would you mind re-attaching it here or emailing me so I may have a look at the offending file?
Would you like me to attach the entire archive, just as I downloaded it, or would you like me to extract the installer file and attach just that?
Do these problems happen with more than one installer?
So far, I've tried downloading the Recently Printed Styles archive, the Modern Extra archive, and (just for kicks) the Alpha Beta Unlimited archive. I've had the same problem with all of the installers.