System process is using a port, why? Windows 7

Is there a generic way to find out which service listens to a port as the System process?

In my case, the System process, PID 4, is listening on the port 443 (https), so another program that needs this port cannot start.

Before, for many years the system did not use this port, so I could use that another program.

How can I figure out what causes the system to listen to that port?

netstat -a -b -o run under elevated prompt shows

TCP 0.0.0.0:443 MyComputerName:0 LISTENING 4
Can not obtain ownership information

I have Apache installed, but when I stop it, nothing changes. I have IIS uninstalled. Other suspects are Skype, CrashPlan, and MySQL server, but they have run on this computer for years without causing this problem. Skype has the option [_] Use port 80 and 443 unchecked. Putting CrashPlan to sleep does not release the port.

I have asked this question on StackOverflow, but it was deemed off-topic there.

There is a similar question on the port 80, but the answers there only say to stop this or that specific service, which does not generalize to another port.

There is another similar question, but in that case the OP comments that the netstat -ab shows svchost.exe as the source of connection, and none of the answers solve the problem in my case.