The version promoted on the new site is 3.4.4.5 but the download link is for 3.4.4.3
JMM_Server_Setup_3.4.4.3 is what I reinstalled to try get running again. The install that has died was the same version also. It appeared that it had started updating but mustn't have :/what versions of Server and Desktop do you have?
And do you remember what you were upgrading from?