I'm not sure what you mean by 'demo'. Unless you're implying something as simple as me recording the matter with video software.

Bumping this as I had to update to 509.1307 to work with some code that wouldn't work with the version I was working around with. With 509, the issue is still there and it's somewhat annoying I have to change between versions just to work on code.

Alright, so lets do some troubleshooting. I want everybody in this thread to attempt these steps.

(I am also doing these steps on /tg/station here: https://tgstation13.org/phpBB/viewtopic.php?t=4979 )
Between every step, connect to a game to see if that step fixed it. DO NOT DO THEM ALL AT ONCE some of the steps override other steps, and we also need to know what step is solving the problem so byond can get the core cause that started the issue fixed.

Starting off, Lets find out what version of byond you are using:

Open the main byond window. (Sometimes called the hub or pager)
In the very top right of the window, there is a white gear icon with a blue background,
Click that and then click "about byond".
In the pop up window that opens look in the bottom left.
You should see 5.0 then below it "version 50x.xxxx" (with x replacing your actual version).
Write that down (the full 50x.xxxx thing) in notepad (or on actual paper if you live in portland you fucking hipster)
Once you finish this guide, you'll need to post the version in this thread.

First things first, Lets fuck around with byond settings for hardware acceleration:
Open the main byond window. (Sometimes called the hub or pager)
In the very top right of the window, there is a white gear icon with a blue background,
Click that and then click "preferences"
Go to the game tab.
Find the checkbox called "use graphics hardware for displaying maps"
Toggle it. (if it's off, turn it on, if it's on, turn it off)

Test that this solved the issue.

If yes: Please post in this thread your byond version, what state this checkbox was in, and what state solved the issue.
On top of that. we need some info about your video card, follow the steps at the bottom of this post for info about what to post.

Otherwise: continue:

Clear cache and settings
Close everything related to byond.
Check the taskbar for any byond icons,
Make sure to click the arrow by the clock to see any hidden icons to ensure anything byond related is closed.
Go to your documents folder.
Find the byond folder
Rename it to byond.old (this folder contains your screenshots, so don't delete it, we will copy those back momentarily
Launch byond and log in (this will reset your saved password)
Go back to my documents, and copy the screenshots folder from byond.old to the new byond folder.

Test that this solved the issue.
If yes, post in this thread that this step solved this issue.

Otherwise: continue:

Upgrade/Re-install byond.
Download this version: http://www.byond.com/download/build/508/508.1299_byond.exe and just install it over the existing one.

Test that this solved the issue.
If yes, post in this thread that this step solved this issue (mention the link you used since there are two). include your old byond version you wrote down from the first step.

if no, Try with this version: http://www.byond.com/download/build/509/509.1310_byond.exe

Test that this solved the issue.
If yes, post in this thread that this step solved this issue (mention the link you used since there are two). include your old byond version you wrote down from the first step.

If none of these steps solved your issue, post in this thread your byond version, what version of windows you are running, and the device description and hardware ids from the video card info section below:

Getting info on your video card
Go to device manager:
(95/98/me/2000/xp: control panel -> system -> hardware tab -> device manager)
(vista/7: control panel -> system -> sidebar -> device manager)
(8/8.1: desktop -> right click at the bottom left of the screen where the start menu button pops up -> device manager)
(10: right click on the start menu button -> device manager)
(7 and up can also just type device manager in the start menu search bar)
Expand the Display Adapter section.
Right click your video card and click properties. (if there are more then one, find the one that says primary or vga or nvidia or ati or intel (if that doesn't help, just use the first one))
Go to the details tab, and in the drop down, pick device description.
copy/paste the first line
Go to the details tab, and in the drop down, pick hardware ids.
copy/paste the longest line. (should be the first line)

Nvidia is Intel based, right?

I've disabled Hardware Acceleration via BYOND, but I still get the issue.

Jay, please follow the instructions in id:1988729 to get debug info.

After getting it to hang for longer, this is a pastebin of everything that was in the debugger.

http://pastebin.com/8K4yJFcV

I get this
0:031> Id: bc34.b8c8 Suspend: 1 Teb: 7f58d000 Unfrozen ~0
^ Operation not supported in current debug session 'Id: bc34.b8c8 Suspend: 1 Teb: 7f58d000 Unfrozen ~0'
0:031> k
# ChildEBP RetAddr
WARNING: Stack unwind information not available. Following frames may be wrong.
00 04b5f94c 74c13744 ntdll!DbgBreakPoint
01 04b5f960 774fa064 KERNEL32!BaseThreadInitThunk+0x24
02 04b5f9a8 774fa02f ntdll!RtlSetCurrentTransaction+0xd4
03 04b5f9b8 00000000 ntdll!RtlSetCurrentTransaction+0x9f

just a note, that (?) link from OP only outputs a bit of text to the client.

about 5 or 6 lines of html rich text.

no open windows.

Its a link that shows to admins next to player names or ckeys admins can click on to get info on that player.

Folks, I need that debug data if this is going to get fixed. I can't fix a bug I can't reproduce unless I have information on how to find it, or dumb luck. A hang should be catchable if I can get this information.

It should show up in the thread info, or else it might be something like byondcore.dll or byondwin.dll.