I'm installing D-Pro. It extracted everything and all the installer windows went away, but Command Center stills says it is installing. Do you think it is still doing anything? Or is it just hung up? I only see a little drive activity.
 
If I try to close the command center, it says that an install is in progress, but I'm beginning to think nothing is going on.

I don't recall specifically, it's been a while, but a number of the installers do seem to go dormant for a while. It's probably best to leave it to do its thing unless it's been silent for a really long time, like more than 20 minutes or so... 

There might be a window open for the Dim Pro installer, where you might have to click on Finish.  Move open windows around, or switch tasks, or minimize things, to check for such an open installer window.
 
Bob Bone
 

Thanks. After about 25 minutes, I shut down the Command Center. It complained that an install was in progress. But when I said to close anyway, it shut down immediately. Then I restarted and D-Pro showed that it was installed. I installed the other components that I still needed to and then I started up Sonar. It successfully loaded all the plug-ins. I tried using Dimension-Pro and the one I tried worked OK.

Same thing happened to me!

I'm with robert_e on this.  I've had this same 'symptom' happen a few times across other applications as well and invariably, it's a message box asking for confirmation, etc.  and it doesn't come to the top.  As a result, it's behind something else.
 
Your mileage may vary