TNS-12541: TNS:no listener

Got a production server that has been having listener problems this week, each morning. Hosted at rackspace.

lsnrctl status some times works and other times gives no listener error. Windows event log shows the listener last came up yesterday, yet lsnrctl show it available and not available this morning. The listener.log shows no errors, only established connections. The listener log grows fast. Connections to DB were about 300, with AWR showing a login rate of about 136/second. Earlier in the morning, when everything worked fine, the login rate was 81/second.
The DB alert log shows no errors.

Here is the status error:

LSNRCTL> status ncdb226
Connecting to (ADDRESS=(PROTOCOL=TCP)(HOST=172.24.12.59)(PORT=1521))

TNS-12541: TNS:no listener
TNS-12560: TNS:protocol adapter error
TNS-00511: No listener

I can't figure out what this means: 64-bit Windows Error: 61: Unknown error

All of this worked fine last week. Could there be a windows port time out or something?

Thoughts?