Is there any difference if you play the track first then hit 'R' to start/stop the recording, then stop the track??

Here is another single clip file.  It won't play. Today's issue.  I end up closing Sonar completely, (not just the file) and when I reopen the program, the clip plays.  Which means the wav file is ok, I assume.  Is there something going on with the timeline, where clips start.... end...??    who knows.   This is nuts.
https://youtu.be/fTgwxiQqKAs
 
Thanks,
Bob E

Chuckebaby suggested the clips might be hidden in a take lane, but I didn't see you address that.  I've had your "disappearing recording" symptom happen for just that reason.  Open up and look at all the takes on the affected track to see if its there but was muted somehow (and therefor not showing in the main track).

Bob EError message says 'degragment' my drive.

I haven't watched all the videos but in this video with the crazy misspelled error message, that project isn't saved. If I make a blank project with some blank audio tracks and just press play and watch what SONAR does it appears to be checking the root of my E: drive over and over again while playing.  E: is the drive where my default Cakewalk Project directory is.  I'd say you should start looking at the folder paths in Preferences->Folder Locations.  I could easily see failures if you didn't have full access rights on the drive specified in the Project Files path.  Most user's don't have rights on the root of C: for example.  But if you want to work out exactly what SONAR is doing you most likely going to have to run something like Microsoft's Process Monitor tool and see where it is trying to write to/read from.  I wouldn't be surprised if the problem is one of the paths in your Folder Locations doesn't exist (or has some other issue).  Or perhaps your Windows temporary directory(s) aren't correctly configured?
 
Here's the Microsoft tool:
https://docs.microsoft.com/en-us/sysinternals/downloads/procmon
 
When you run it setup a filter so that it only logs process names that contain "sonar" and then press play inside SONAR and see what it's trying to access.

I've watched your vids and I agree, this is weird stuff. I think it all has a common root cause, and it looks to be hard drive related.
Is it possible to list the contents of your "directory paths" that Sonar is using ? Maybe there's a clue there. What drive are you creating your projects on? Audio folders?
 
 

 I am looking into various suggestions. Thanks to all. Chuckebaby mentioned that he saw that the take lane button in track 2 was blue, meaning that there was a take on it. Invisible, though as I couldn't see it when I opened up the take lanes. The button probably shouldn't be blue. Hmm
Also, I don't think that would stop me from recording onto track 3, as I tried later in this video. I appreciate your input greatly! Thanks again! Still working on solutions.  I plan on recording this evening and keeping an eye out for the causes.
I will try the process monitor tool from Microsoft.  Thanks msorrals for that and the 'filter' detail.  I've tried two drives to see if there was a problem there.  Neither drive was my C: drive.  Everything in my folder preferences are set to my D drive, which is 7200rpm and in fine working condition.  (I tested out a SDD drive earlier in the week, pointing everything there.  Still had these issues, so now I am back to the 7200rpm drive)

Clicking on the take lane button of an empty track turns the button blue and adds one empty take lane. (the default take lane).  The button stays blue until you delete (hit the x) the take.  Then it is normal.  I believe this is the default.
So, the blue take lane button doesn't mean there is any data on the track.

This may or may not be related, but I have seen recorded clips go weird and corrupted immediately after recording, although they did not disappear. Reinstalling the audio interface drivers fixed the problem. Anyway, I believe that it's worth a try in your case. Maybe update them if necessary.

With the disappearing recordings, are the clips in your audio folder? (i.o.w., exists but is it just not being displayed?)
 
There is just too much unrelated and crazy stuff happening here. The misspelling 'degragment' is indicative of how often this error message has been seen.
 
Like stickman, I tend to think it's hardware failure we're looking at. Memory, HD driver hardware, faulty power supply (I had one with a leaking smoothing capacitor. Worked fine superficially but did crazy things when more power was drawn, like writing to HD)
 
Is this a new PC, dedicated to music? Are other programs also misbehaving? If you had another DAW installed, this would be ideal because it will access similar drivers and hardware. Reaper is free with nag and could be used to try.
 
Edit: In your videos you do actually say you have other software, video editing for example which would take hardware to similar limits as Sonar, and they work fine.
 
OK, I give up. I have no further ideas to contribute.

Update:  this was more wishful thinking.  This is/was not the problem.
 
I'm keeping my fingers crossed, but I may have found the problem.  I occasionally use an accompaniment program  that only works at 44.1 kHz sample rate.  Band in a Box.  Because of this, my default Windows audio needs to be set at 44.1k and 16bit. 
I only use an ASIO driver/interface with Sonar and all my projects are 48k 24bit. I don't use, or run, Band in a Box  while Sonar is running, but there was a virtual audio cable enabled on my system, linking Windows Audio to an ASIO input.
I disabled the Virtual Audio cable, and so far, I haven't had these issues.  I'm keeping my fingers crossed because I had previous been able to record/track with no problems, even with these settings, (for a while, anyway)
 
The virtual audio cable had worked fine in the past. (I use it to do tutorials, getting ASIO to stream to desktop capture programs such as Camtasia 9).  However, I believe I had Windows Default Audio set to 48k 24bit at that point.  Hence, no issues. ?
 
Maybe all these issues started when I changed Windows Audio to 44.1 to accommodate Band in a Box. It was a while ago that I did this. (and I've been having issues for a while).   I didn't consider the Virtual Audio Cable as the problem because I never used it with Sonar.   It was enabled long ago on my system, ('set it, and forget it') ,  ('out of sight, out of mind').
Although I wasn't using it in Sonar, having it enabled on my system could, maybe have been causing these mind-boggling issues?   I'm hoping so. 
 
I will keep testing and recording to see if this is the problem.  Many thanks to all who have made suggestions and taken the time to help!!  I will update this to confirm, (hopefully) that this was the issue.  Does this make sense?
Thanks,
Bob E