ClickOnce Woes with VSTO's

So, I'm trying to redeploy a VSTO application and I get the following beautiful, beautiful, beautiful error...

Unable to install this application because an application with the same identity is already installed. To install this application, either modify the manifest version for this application or uninstall the preexisting application.

It's frustrating, because I know it has been uninstalled and everything is fine.  Registry doesn't even show it deployed.  Commence "tearing out my hair" mode.

And then, I found the problem.  Apparently, VSTO's can sometimes screw up the ClickOnce cache.  Awesome!  So, that being said, if you run this from the command line (and it's very fast, so don't freak out and think nothing popped up/succeeded) all will be better:

rundll32 dfshim CleanOnlineAppCache

And thus, order and balance was restored to the universe again... for a short time.

MSB3326 "Cannot import the following key file: ."

Due to restrictions, I'm limited in some of the things I'm allowed to post, so these updates will be less frequent than before... which isn't saying too much.

In any case, I bumped into a new problem: MSB3326 "Cannot import the following key file: ."

Where is the key file?  Why is it blank?  I know I'd deployed the key and everything was fine prior, so what was the big deal?

What this means is that it cannot access the key file -- maybe you're like me and have to use an alternative administrative account for building and keys and the like.  So, I had to manually open certmgr.msc as the same administrator that was building the project.

After that -- all was pie in the sky.  Things work, life is good, and finally there is an answer to this horrific question.