The ports used by the qserver depend on which instance you are running. There's a known issue where instance 1 will use the same port as the Cache Channel Service (1099). Perhaps someone recently installed the CCS?
If so, you might need to change Fredhopper to start instance 2 instead of 1 - which will run the qserver on port 9180 instead and hopefully avoid the port conflictsuse different ports. You can do this by adding "-I 2" to the command line when starting the qserver. Don't forget to update your SmartTarget configuration file too with the new URL (the qserver will run on 9180 instead of 8180).
You may also be able to change the port(s) of the CCS, but I'm not entirely sure how you do that.