DNN is installed to my virtual root and yes, I've got full writes to that directory.  I had my web host set the directory permissions to read/write/change before beginning the process.

Since I know for a fact the files that I'm trying to hit are where I'm trying to hit them, the 404 error must be caused by a structure change, I agree.  Is there a structure change betweeen 4.4.0 (install) and 4.4.1 (upgrade)?  That would be most surprising.  Perhaps there's a URL in the database that's been fubar'd but is needed so a security issue can be tested out?  It seems, since I'm getting the 404 error on hitting any aspx that there must be a standard response.redirect() call being made.  If that's the case, it would most likely be to an authentications page but I don't know enough about the system to determine which that might be.

At any rate, I very much appreciate any help that can be offered.

Thanks in advance.

Robin