#1 and #3 sound like software issues that may have existed in X1d and are meanwhile fixed. I never came across them myself but I haven't used X1d long enough (X2a was in use for long time, X3e still is installed and used occasionally). I'd install the demo and work it for a while, should be easy to find out if it is fixed if it is happening frequently on your system.
 
#2 maybe a software issue (e.g. performance related inside Sonar), so there is a fair chance it works better now since we have just got 2 rounds of performance improvements, many related to synths ... or it is one of the strangest hardware issues ever (but you won't get any support for X1d, so that's a dead end street)
 
I would also recommend upgrading. New features are really worth it as mentioned above. Plus there is good support for Platinum with many issues being addressed that we listed/discussed/reproduced in this forum.

Time to upgrade to Platinum, best Cakewalk program ever!

konradh
2. I lose audio if "too many" VIs are installed.  "Too many" can be 7, or 11, or 12 or some other number.  Task manager says I have plenty of memory and CPU available.

Have you tried increasing the default value or MIDI Prepare Using Buffer from 250ms to 500ms or more?
 

Oh? Well, if number 2 really IS due to the "Prepare using xxx milisecond buffers" setting,
then perhaps it'll help to say that I had cause to open my X1 recently and I found I'd
needed to set it to 1000ms to get it to work without losing midi notes. And I only used
Session Drummer back then.
 
It was announced back then that, as of X2 (I think?!?), the default value would be
increased to 500ms and it seems still be that in Kingston.

Sorry, this is one of those old issues that come up time and again, I assumed
konradh would be aware of it.

Konradh did have issues that seemed to be system specific.
This is a Sweetwater system, wasn't it?
I would go ahead and "take the plunge" as most are suggesting.
BUT, there is the demo, download and try it first!
I would do a system image first, just in case.
That way if Platinum introduces new issues for X1, you're not stuck.
Just a nickel98...
Tom

Platinum is leaps and bounds ahead of X1d. So many hundreds of annoying bugs and oddities have been fixed since then. If upgrading is financially viable to you I would advise it strongly. You might have a couple of weeks of "huh" getting to know a new version but pretty soon you'll be wondering how you managed with X1 for so long - Platinum is so much more stable, faster and just works great.

However if you're still against upgrading I would recommend doing a complete removal of everything Sonar related and a fresh install. There have to be X1 uninstall instructions somewhere which tell you what to delete in the registry etc.

My apologies for failing to reply sooner to all the excellent comments.  I have been on the road almost constantly for a while.  Thanks very much.
 
1-Based on all advice, it seems best to take a system image and then upgrade.
2-I do have some concerns about getting all my software libraries working after an upgrade, since this was a problem with the initial install.  I have a lot invested there: Vienna Special Edition Vienna Dimension Strings, Hollywood Strings, RealGuitar, RealStrat, RealLPC, several Scarbee Basses, EZ Drummer, Kontakt libraries...well, there are quite a few.
3-I am running on a Sweetwater system and, with all due respect to Sweetwater and the many hours they have spent trying to help, I fear something was set up wrong to begin with.  Maybe an upgrade will resolve things, or at least point us to the issue.
4-I have almost bought vocal sync software several times because I use a LOT of harmony parts and do a ton of hand work in Melodyne; so, needless to say, I am excited about having an integrated solution.
 
With all I have invested in software, a Sonar upgrade, though certainly not cheap, is not a huge investment relatively speaking.  It is more that I am a little cowardly about rocking the boat and making things worse, but what the hell: you only live once.
 

You should find the upgrade process pretty easy, intuitive and fairly speedy (depending on your internet speed).
 
Keep us posted with your progress, looking forward to reading about it

Thanks, buddy.
 

konradh
 
With all I have invested in software, a Sonar upgrade, though certainly not cheap, is not a huge investment relatively speaking. 

That comment is what sticks out most for me. I ran X3 in tandem with X1d for a long time because a friend stopped at X1d and I needed to keep it up and running. Just the experience of running them side-by-side for so long made me realize the limitations of X1d and that I would never return to it as a "main stay." Platinum has made a lot of enhancements and bug fixes over X3 even, with a much better response time to show stopping issues due to the new model. X3 had one hot fix IIRC, and Platinum gets them in under two weeks when needed, and can roll back to a previous version.
 
As far as installation, a system restore point as well as a C drive image prior to installation would be highly recommended. I did learn first hand when I rebuilt this machine in July do NOT installed X1 stuff after Platinum (it messed with my staff view font).
 
Another mitigation for potential issues is to do a save as on projects being pulled forward with the version in the title. Just in case something happens, the previous version's cwp is fully in tact and can be completed in that prior version. In your case, please make a habit of doing that save as religiously, such as "[file name from X1d] - Plat-K.cwp" etc.