Access denied messages running Nexus as admin

I am trying to upgrade from v2 to v3. I was able to install successfully the first time, but then I had to reset my admin password in the middle of upgrading from v2. I am trying to do a clean reinstall of v3 to start over. I keep having problems with the db folder. I get messages like this:

Caused by: java.io.FileNotFoundException: D:\sonatype-work\nexus3\db\config\database.ocf (Access is denied)

The messages vary. I didn’t have this trouble installing it the first time. I have tried deleting both the program folder and the nexus3 folder of the working directory. What else can I try? I am running it in Windows from a command prompt with admin privileges.