On one computer but not the other I get the error message “activating best chain” for a minute or so after startup when trying to do other functions. What does that mean? Why on 1 PC and not the other?
I am getting this message too…How to fix this?
I just started mining today (beta) and now stuck …
“If it is still stuck trying to find the chain, go ahead and run a ./src/zcash-cli stop to stop it (or kill the PID with system monitor) and restart it with ./src/zcashd -reindex”
that worked 
It worked until another server start…then all over again and again 
Same Problem, after upgrading to rc4. First run worked. After it got stuck without any cpu usage. Maybe I need to clean something?
Running
./src/zcashd -reindex
Removing and reindexing solved it
rm -rf ~/.zcash/testnet3
./src/zcashd -reindex