Windows Defender is the only anti-virus on the machine at this time. I just tried a fresh reboot, and turned off Windows Defender. Then tried Save As PDF once again. Same issue. Doesn't seem to be associated with Windows Defender.

Not using any cloud saving/syncing. Only saving files to a local SSD. No auto-syncing tools installed at all.

Thanks for detailed reply to earlier queries. This helps to know that save happens successfully. Do you have any antivirus enabled with real-time scanning - it can cause a conflict as soon as a new file gets created? Also, is your save location a cloud sync folder (like OneDrive/Dropbox) or a local folder?

Further Information:

This issue happens even if Illustrator is the only program running. If I reboot the system, and ONLY open Illustrator, the first time I "Save As.." a PDF, it freezes my task bar.

I have updated my BIOS to the newest (non-Beta) version. All my hardware drivers (video, audio, LAN, AMD chipset) drivers are up-to-date. All Windows Updates have been installed.

QUOTE:

1. After step 3 (as mentioned by you), PDF setting dialog comes in. Do you see that or not?
2. When you click on Windows Start Menu or any other on task bar, is the Save complete in Illustrator or not?
3. Would also like to know if the Save gets completed, is the file saved correctly?
4. Can you also tell me a little more about the Step 4? What's the objective of accessing Window Start Menu or any other operation through task bar while save is going on .

----------

RESPONSES:

1. I still see the Save As dialogue box (for what it's worth, the same issue happens if I use "Save a Copy.." instead of "Save As.."). I can choose options from all the tabs (General, Compression, etc.), and can click the Save button to initialize the save.

2. The PDF save completes successfully.

3. The PDF is saved correctly. My chosen Save As options are applied correctly. No file corruption.

4. I am usually trying to open my Browser (Firefox - where I have my project collaboration site running (Basecamp)), Photoshop, or Windows Explorer, just to manage the file I just created. I have those programs on separate monitors. Those programs are still accessible on the other monitors, but not through the task bar, as it is now frozen and doesn't respond to left or right clicking.

-----------------

And one more further bit of info: Once I have restarted Explorer through the Task Manager, it seems to fix this issue for awhile, as it doesn't happen again (repeating the steps outlined in my original post) when saving another PDF file. I have seen it randomly re-occur after a couple hours of work, however, and it is 100% repeatable if I restart the system. If I try it again immediately after a restart, the same issue happens again.

This only started happening some time in the last couple of months. I have tried older versions of Illustrator, multiple versions of nvidia drivers, rolling back most recent Windows Updates, and even re-installing Windows 10 completely. The issue persists.

Some questions here to understand the issue better
1. After step 3 (as mentioned by you), PDF setting dialog comes in. Do you see that or not?
2. When you click on Windows Start Menu or any other on task bar, is the Save complete in Illustrator or not?
3. Would also like to know if the Save gets completed, is the file saved correctly?
4. Can you also tell me a little more about the Step 4? What's the objective of accessing Window Start Menu or any other operation through task bar while save is going on .