abacab
Then insert each synth and try to load the presets, and see which one has missing samples.  Simples! 

These are samples not programs. It may be possible to guess which programs reference the samples. My RPro has ~19000 programs. While that looks like a lot, I would not be surprised if others have many more if they purchased many of the DSF DPro expansion packs.

I had a similar experience recently. When I installed the Sonar documentation files on my new computer, the chm and pdf files ended up in the top level of the C-drive, i.e. not even in any folder. Nothing, except maybe a couple of system files, should be at the top level.

mettelus
Hmmm, I assumed this was DimPro, but the prog files are not present (banks 26-98 do not show up in the DimPro browser), *and* my DimPro browser has different names -  05 - Drums, 13 - Leads, 18 - Splits, 19 - Drum Grooves. These all have prog files that load into DimPro. The ones in the OP do not.
 
I installed DimPro to a bare slate, and used the default (C:\Program Files\Cakewalk\Dimension Pro\Multisamples) directory, and *most* of everything installed there (around 4GB).
 
Is this from the DimPro installer I used (I used 1.5.5.16 (newest), but have a others I kept)?

I had an occasion or two when files don't show up in Dim Pro. Restarting didn't help.  What fixed it was hitting F5 when the Dim Pro browser has focus.

One more thing, an easy way to rule out Rapture is look in the folders for audio files. DPro and Rapture Session/Pro install flac files. Rapture Classic does not support flac and installs wav files.

Virtual B3 was a Dimension expansion pack.  I am guessing though that this might be Sound Center.

I just got a chance to check this a little further and found something even more odd. In Dimension Pro, the browser still lists the original programs (e.g., 05 - Drums) and plays them fine (even after I lumped them all together). I installed sforzando this evening, and in that "05 - Guitars" is listed instead of drums... sforzando also loads them all without issue (but doesn't see the drums, as DimPro doesn't see the guitars). Incredibly odd, but seems as though the .prog files are all present, but Dim Pro will only load one set (similar to sforzando, but in reverse)... it is almost like Dim Pro dumped all of its conflicts during installation into the C:\Multisamples folder. I have been playing with a cwp with both DimPro and sforzando inserted, both playing from their "05" bank.
 
Another odd (maybe Win10 specific) issue with sforzando standalone... this thing is literally importing ALL samples at an incredibly slow speed (40MB/sec from an SSD). No clue why it is doing this (v1.933), since the VSTi in a host is instantaneous. It is almost like it is trying to resolve these conflicts during load in standalone mode. It did open a few times after only 15 seconds or so, but now seems in a "do loop" of loading and doesn't stop. I will circle back on this one later on, since the ARIA player for Garritan relies on this and now my ARIA player is mucked up in standalone too. I will try moving DimPro samples out of view and see if that affects it.
 
Quick edit: I moved DimPro's samples out of the Multisaple folder and sforzando is still taking forever to load in standalone mode. I will try to figure out what it is doing later on when I have time.
 
Update: The issue with sforzando was Win10. Setting the compatibility mode to Win7 resolved it (but only on the first launch, so still an issue).

I have not looked at sforzando in some time but the last I looked it works with sfz and audio files not the DPro prog files. The DPro program browser does not look at the multisamples folder directly but displays the contents  of "C:\ProgramData\Cakewalk\Dimension Pro\Programs\programs.lst" which is based on the prog files found in "C:\ProgramData\Cakewalk\Dimension Pro\Programs." DPro uses the path specified in Multisamples Folder in HKEY_LOCAL_MACHINE\SOFTWARE\Cakewalk Music Software\dp to resolve the location the sfz and audio files referenced by the prog files.

BTW, I should mention that Rapture Session/Pro should be installed last. This insures the Rapture Session/Pro installers see the legacy synths. If installed out of sequence, re-run the Rapture Session/Pro installers (just the plug-ins not the content) so that the legacy entries make it into the registry and program folders.

Thanks Steve. I will run back through an install cycle on these later on (I am running out of steam now). I did just do a check to confirm that there are *no* "05 - Guitars" prog files on the entire machine (only a sample directory), so not sure how sforzando is doing things. DimPro is loading prog files, sforzando seems to loading by samples (confirming your post above). The mismatch is between the two... 05 is "Drums" in the programs directory, but "Guitars" in the Multisamples.
 
sforzando in Win7 compatibility mode only launches in standalone cleanly one time, after that it goes back into its "do loop," so will research that a bit later as well.

After reading this discussion I looked and, behold, I have a C:\Multisamples directory too with 412 MB of content. What to do, what to do?