rpm transaction lock error?

[Neal Becker]

I tried installing vivaldi-beta on f23, and got:

 sudo rpm -i ~/Downloads/vivaldi-beta-1.0.303.52-2.x86_64.rpm 
[sudo] password for nbecker: 
warning: /home/nbecker/Downloads/vivaldi-beta-1.0.303.52-2.x86_64.rpm: 
Header V4 RSA/SHA1 Signature, key ID bf1700f8: NOKEY
warning: Generating 2 missing index(es), please wait...
error: can't create transaction lock on /var/lib/rpm/.rpm.lock (Resource 
temporarily unavailable)
error: /tmp/google.sig.gc6XhF: key 1 import failed.
Redirecting to /bin/systemctl start  atd.service

Any ideas on these errors?