MSI Installer Pkg. blocked by Windows Installer

Hello all. I really need your help. I've tried to open a downloaded file - TinyWallInstaller.msi - , but without success. I've learned that Windows blocks opening this and many other file extension types because it rates them as "high risk" or "invalid" with the pop-up : " Publisher Could Not Be Verified". I also came across a simple tutorial that does unblock this, but it doesn't apply to Vista Home Prem. - my O.S. So, that said, I'm looking for a good workaround that will enable me to unblock and open this neat firewall program. My experience is somewhat limited - would hope to avoid command prompt and registry editing if possible. However, at this point I'm willing to try just about anything! Please help!!!

Hi.

Have you tried going into control panel and disabling the windows firewall?

Hello windows8. Thanks for responding. I think you may've misunderstood me - I probably wasn't clear. I 'm not having problems downloading the file - it's sitting in the download file on my computer. When I click on it to open, up pops this window: "Windows Installer - This installation package could not be opened. Contact the application vendor to verify that this is a valid Windows Installer package."

The download originated from a great article at Daves Computer Tips » Free Computer Help, Tips, News, and How-to's titled "TinyWall: The best thing since sliced bread?" by Jim Hillier, 6-12-2012. I mention this because comments posted after the article show that others were using the firewall after reading the article ( Dave's provided two links to download program).
So, I'm stuck with what another site conveyed is a default security setting by Windows, rating certain file extensions as " high risk" - so it simply won't open them. There's a way to edit that policy in the Attachment Manager>Inclusion List File to "Enable" in Vista Business,Vista Enterprise, Win. 7 etc. But this - as I learned - isn't avail. in Vista H.Prem. or Vista Basic!!! *PS: And yes - just for kicks - I did try disabling Windows firewall as you suggested, but it didn't help. So alas, I'm still on the hunt for that illusive solution!