Hey guys,
It seems that the Windows 1709 update screwed up something. I am getting the "Windows Installer" pop up when launching Sonar Platinum. The pop up hangs for about 1/2 hour and then I get "Install Server Not Responding" pop up. Sonar then loads in the taskbar. Everything is loaded in the Command Center  and everything has the up to date green button next to it. 
I had the same issues with my Waves Instruments and XLN Addictive Drums and Addictive Keys. Those issues were easily fixed by reinstalling the plugins from XLN Online Installer and Waves Central.
 
Does anyone have a fix for Sonar? Have anyone tried to reinstall Sonar?
Thanks
JT

Does the installer say what it's trying to install? It's most probably something to do with a VST plugin when Sonar is scanning for new plugins. I doubt if it is a Sonar installer.

I just get the blue and grey "Preparing to install window". It does nothing and hangs for about 1/2 hour.
After 1/2 hour I get a 2nd pop up "Install Server Not Responding". It will also hang until I hit "cancel"
When I hit "cancel"Sonar  loads and all my 176 plugins load properly.
 
 
 

Try looking in the Event viewer under administrative tools and check "Setup" and "Application" under windows logs for the time it happens to try and identify what is causing issue.

Ok. Finally found the issue. "Yamaha Steinberg USB driver" was causing the issue. I deleted it and everything is back to normal

Thanks JT2014, the Yamaha Steinberg USB driver was my problem also. After I uninstalled the driver SP ran normal. I then reinstalled the Yamaha Steinberg USB driver v1910-2 and SP ran with no problems,hope this works for you also.

I removed the Yamaha Steinberg USB driver because I didn't like it at all.

Try to reinstall the yamaha steinberg usb driver. I had the same problem after a windows update. 

Bump! I've been fighting this for a while now. Uninstalled the "Yamaha Steinberg USB driver" and I am able to open Sonar again. 

I was just hit with this issue running BandLab Cakewalk.  Glad I found this article!  Back in business.