I know a similar issue has been added to the knowledge base, and there might be other forums focusing on this particular issue as well, but I still need to get it out there.
 
The error I've been experiencing while completing the installation of SONAR Professional is not with "Exit Code 0x3" but with "Exit Code 0x5." I am not sure if that means the same thing or if it focuses on a different problem with a different solution (still dealing with the installation of the components, though), but it is preventing me from installing these components.
 
I've been looking up on this issue, and I did try to follow along with the steps and methods, but it just gets confusing as it goes along. I don't know what to change in the Registry Editor. They did not tell me what registry key to change.
 
I got the error message when it was just about to finish installing the Professional Instrument Collection, and I do need some assistance to help me get through this.

The full error message and Windows Version may be useful in figuring this out. It might also help to know if this is a manual install or running from the Command Center. If using the Command Center was the "Install All" option selected?

Error 5 = Access Denied. That happens when a file is in use that an installer is attempting to overwrite, or a file has been marked Read Only. For example, a SONAR update will fail that way if SONAR is currently running.
 
Did the message specify a pathname?

Yes, I chose "Install All."

Yeah, the pathname says the following:
C:\Program Files\Cakewalk\Shared DXi\PSYNII\PSYN II.dll
I was, however, really confused with what it actually leads to.

"Install All" skips the parent (in this case SONAR Professional) and attempts to install all the items under it. I would try installing the SONAR Professional line item first. Then try reinstalling the Professional Instrument Collection,
 
If you are running Win7 make sure the OS is up to date. Also if you are not in the habit of rebooting frequently, reboot before attempting the installation.

Here's the thing:
When it was installing these items, the actual Cakewalk SONAR Professional digital audio workstation itself installed first before the other components. Sometimes, the way they install these items do not go in the same order.
 
I use Windows 8.1, by the way. Does my computer still need to be up to date?

Try running CCC as Administrator. I don't have that file so I can't check, but it's possible PSyn is an ActiveX DLL and the failure occurs when CCC tries to register it. Windows has made it more difficult to alter parts of the registry as a security measure, requiring some older DLLs to need Admin access to install.

Steve, I did actually tried your strategy on rebooting and installing each component one by one, and it had worked out. I do appreciate your assistance.