Check out QEMC --> Services. Are all services running? My guess is that Server service is down (even though it will appear to be running in the Windows services console)...If so, what OS is your server running, and what OS is your Domain Controller running?
In services.msc try changing your Qlikview Server service from the Pub account to the Local System account and restart the service. I've seen this problem only 1 time before, and it's very hard to reproduce, but this worked to fix it last time.
I'm not sure why this happens. I'm working with Qliktech Support to try to pin down the issue, but we haven't found anything concrete yet. My best guess is that it has something to do with a restrictive GPO setting, but I'm not sure which one.