There is no option for a custom install with the installer I downloaded.
 
Installers for Windows programs should not be creating new directories on the root of the C: drive in 2014. Per-user data should be in the user profile, machine-wide data should be in C:\ProgramData.

Also, disabling UAC is a dumb thing to do, no offence. It's there to protect you from security risks which are quite significant these days. Any app that requires those specific privileges during installation can ask for them.
 

@Kylotan - VERY happy this seems to be working for you now.
 
It is my recollection that there is an option early in the install to do a custom install, and I also seem to recall getting the opportunity to change location paths for content, so I am a bit confused.
 
Additionally, and in any case, if you go to Edit>Preferences>File>Folder Locations, you will see the different folders where you can relocate them to a path of your choosing.  To do so, I recommend that you do a copy/paste operation, and only then removing the original content, followed by altering the location in Preferences and making sure Sonar finds the relocated content.
 
All my Cakewalk Content for all of my retained releases lives on my D: drive, as does all data.  Only the OS, applications, appdata, and ProgramData live on my C: drive.  I have my user libraries all moved over to the data drive (D:) too.  While I could have chosen to have Cakewalk Content live in ProgramData (I suppose) - I didn't want to do that.
 
Anyways, since this seems to be working for you now, do you mind editing the subject line of your initial thread post and adding something like 'Solved'?  That would make it easier for future folks looking for solutions to similar issues to find an answer.  This is certainly not a forum requirement - just a helpful thing to do.  :)
 
Thanks, and again congrats.
 
Bob Bone
 

This is the trial install, not the regular install. I have always had more options in the past when installing Sonar, but that wasn't the case for this trial download.
 
One thing Cakewalk does that is frustrating is put its sample content all over the place. It seems like a different location for each version. I've had to move things out of My Documents before, for example. To add insult to injury, in this install it has actually used the correct location of C:\ProgramData\Cakewalk\SONAR X3 Producer Trial for a lot of data - but then pushed a bunch of stuff into C:\Cakewalk Content too. It shouldn't be doing this, as it complicates backup procedures, as well as making it awkward to find content when you need it. It's great that Sonar lets you move the directories (and I always do this), but the defaults should be in the proper places, and ideally there wouldn't be fifteen different paths to amend.
 
I don't consider this thread solved as such; there's been no explanation for why the installer was getting the path wrong. Ideally someone from Cakewalk will see this and realise that something needs fixing.
 
As an aside, I'm amused to see that the 'Migrate Sonar Preferences' box doesn't appear to have been changed since 1996. And still has misleading checkboxes you can't use. And produces a totally misleading warning about my audio data files. And failed to migrate any of my paths from 8.5 over, despite finding the .ini file. *sigh*

This error condition is certainly not widely reported, and it appears that other than understanding why it may have occurred, and perhaps seeking dialog on why they choose locations for components and/or content, the error condition itself seems to have been resolved and the installation completed.
 
Good luck with it then, I'm out.  
 
Bob Bone
 

Kylotan
Also, disabling UAC is a dumb thing to do, no offence. It's there to protect you from security risks which are quite significant these days. Any app that requires those specific privileges during installation can ask for them.

+1.