@bellyband Hmm.....
I was going to suggest deleting the preferences in the registry (probably still at "Computer\HKEY_CURRENT_USER\Software\Pure-Data" ) but I see you have tried the -noprefs flag.
As it is starting wish it is getting part way through its startup sequence.

You don't need to start a patch as Pd starts...... out of the box you wouldn't have one to start.
Audio problems can stop Pd starting, even though dsp will not be running as it starts.

Create a shortcut to pd.exe in the bin folder. Edit the shortcut to open pd.exe with the -noprefs and -noaudio flags.... don't open a patch with the command.

If that doesn't work then try a portable version of Pd.
puredata/info seems to be down at the moment.
When it is back up go to this page ........ http://puredata.info/downloads/pd-extended ..... I remember that the page will allow you to navigate to recent versions of Pd vanilla.
Find a portable version of Pd for Windows...... it will be a .zip file that you can download and run anywhere (it does not require installation).
Unzip it into a folder on your desktop and double-click the Pd/bin/pd.exe binary.

If that doesn't work then try starting that binary with the -noprefs and -noaudio flags in a shortcut rather than a cmd window.

If that doesn't work then create a new user in windows, and see if that user can run Pd.
You could have a corrupted user profile in Windows 10.
And then, for the moment, I am out of ideas, but you could try uninstalling windows updates that have been installed since just before the problem first occurred.
David.

@bellyband I see that you are trying to start pd.com and that name could be resolving in DNS to the internet. Try starting pd.exe directly from the Pd/bin folder.
As @fishcrystals noted....... when you double-click a patch to open Pd it is pd.exe that is started.
But maybe you are only trying to start pd.com to get the stderr information in the cmd window?

If that doesn't work then there could be a problem with your DNS server.
The hosts file overrides DNS, so if you specify the localhost in the hosts file that might help.
The lines starting with # are simply comments......

# 127.0.0.1 localhost

# ::1 localhost

Remove the # symbols for them to be effective......
127.0.0.1 localhost
::1 localhost

The file you need to edit is ........ C:\Windows\System32\drivers\etc\hosts
Use administrator rights to change it.

If you check the traceroute in a command prompt you should have only 1 hop...... the first number in the line returned......
Both localhost and 127.0.0.1 should return the name of your computer

David.

@bellyband This is how Pd starts up......... https://puredata.info/docs/developer/PdStartupOrder
The last error ..... in your first screenshot....... is the first error according to the tk manual... all the others then follow.
As no Pd version is working for you I think that pd-gui.tcl is not managing to connect Pd to the GUI (the wish.exe program in windows).
It shouldn't be a firewall issue as they both run on localhost..... so have a look at your host file. Sometimes it is corrupted by the heavy hand of your isp, a browser add-in, or by a virus.
Have a look at this thread....... and let us know how you get on.
https://forum.pdpatchrepo.info/topic/9268/pd-extended-not-working/11

Also...... if you never re-boot your computer.... check in task manager that pd.exe, pd.com, and wishxx.exe (xx = 85 or 86 or 87?) are not already running.......
David.

@Eric12368 We will need far more specific information about your project........ the computer and os running Pd, the microcontroller etc., but you should probably use the [comport] external in Pd for the serial communication.
Please upload to this thread the Pd patch that is not working, and let us know what sensors and code you are using with the microcontroller as any problems with the data are more likely to occur at that end, but can often be resolved within the Pd patch.
David.

@oid Not looked at the patch, but my best guess is that it had a slider attached at some point, and that was removed without removing the audio operator....?!
David.

@oid I understood (from the op) that it is the window control that is not working....full screen and removing the menu bar. I think that if the attribute control doesn't exist in their window manager then there is no way that they can address the issue, other than using a different window manager...... probably..!?
It's unusual that the window manager doesn't give fullscreen control though.

I had a good go at tcl/tk years ago, but you are way ahead of me.
David.

@EwanBristow Not all wm (window manager) attributes are supported in Linux.... some window managers support more than others......
You will be able to modify the plugin.... it is just a text file.... if you can find a workaround...... https://wiki.tcl-lang.org/page/wm+attributes
David.

@bklindgren From the screenshots it looks as though [tabread~] should be 8 channel, but for it to be 8 channel multichannel it will need 8 arguments (the array names).
The help file says it becomes multichannel when it has more than one argument.
Maybe the arguments can all be the same...... referring to the same array.... if that is what you need.
I could easily be wrong about that..... with just screenshots to go by.
David.

@nicnut Put a [change] into the Pd send for control of the leds too... as when they change they are probably sending their state back to Pd.... and Pd is probably sending that again..... etc.
David.

@nicnut My best guess is that you are suffering Midi feedback...... so when Pd sends a message to the controller it is sent back to Pd and Pd sends it again to the controller... etc. etc.
The same thing happens of course when you press a button on the controller.
There should be a setting in the controller that will stop received messages being sent back, but if not then you will have to block them in Pd, probably using [change]
David.