Plesk downtime

[PolitisP]

Hello,
Yesterday I noticed that I couldn't access any website on my server for few minutes and it happened twice.

At first I thought plesk was updating so it terminated apache server, but this is what I see when I log in plesk:
The system is up-to-date; last checked at Oct 31, 2012 04:03 AM

After checking sw-cp-server/error_log I saw this:

2012-11-05 13:09:50: (connections.c.309) SSL: 1 error:1407609C:SSL routines:SSL23_GET_CLIENT_HELLO:http request
2012-11-06 08:54:08: (server.c.1543) server stopped by UID = 0 PID = 11431
2012-11-06 09:00:23: (log.c.166) server started
2012-11-06 15:54:53: (connections.c.309) SSL: 1 error:1407609C:SSL routines:SSL23_GET_CLIENT_HELLO:http request
2012-11-06 19:45:49: (server.c.1543) server stopped by UID = 0 PID = 24799
2012-11-06 19:53:00: (log.c.166) server started


Are these 2 error messages somehow related? And how can I find what caused this? (PID 11431 & 24799 don't run anymore)