I havent used pentagon in awhile but went to go open it and experiment with some sounds however it says there was an error opening it and that it may need to be installed again. Where can i find the installation for it? I do have Sonar 8.5, x1, x3 and platinum installed on the computer.

This error us usually the result of having insufficient permissions to access the Pentagon registry entry. Either run SONAR as administrator or modify the permissions of HKEY_LOCAL_MACHINE\Software\rgc:audio software\DXi\Pentagon I

Thank you Scook, it worked. Simple step i over looked.

You may not have to re-install although this solution would not be recommended by Cakewalk and use it at your own risk. First to use Pentagon in Platinum you must run as admin. If still not working this is what I did I created a folder in the VST folder and named it Pentagon then I moved the pentagon dll (there is two dll there) and copy the rgcaudio folder to the Pentagon folder I created open up Platinum as admin (that file that was move was copy back to its original location) now you should have a new synth in your VST folder named Pentagon open it up I got Pentagon with VST features and when I open in earlier version of Sonar I did not have to run as admin. If you did not get Pentagon with VST features open Platinum again still as admin and bring Pentagon in from its DXI folder.
The above was done in 64 bit I do not have 32 bit Platinum installed yet I do have 32 bit X3 installed and have no problems with Pentagon in 32 bit.
 
If this is too risky to try yes you can re-install Pentagon I would recommend doing from Platinum as this would give you its latest version.