Have you tried these?
https://community.bistudio.com/wiki/Arma_3:_Unusual_process_exit#0xC0000005_-_ACCESS_VIOLATION

Follow the steps here:
https://community.bistudio.com/wiki/Arma_3:_Unusual_process_exit#0xC0000135_-_STATUS_DLL_NOT_FOUND

Graphics card driver is up to date!

What you mentioned is not a vanilla feature. You can't go prone with the launcher in your hands in the base game. So blame the mod you're using (possibly ACE)
The only thing I could reproduce was the player standing up when he's prone, and switches from No Weapon to the Launcher.

In T156969#2217395, @longtime wrote:

The hunchback bug also occurs with civilians. These are spawned in the mission by either 1) civilian module or 2) with createAgent. Very little scripting otherwise, just a couple of event handlers (killed, firedNear) attached to the civilian unit.

The mission ran for several days and each new mission area spawned "hunchback" civilians like the screenshot. All other Blufor and Opfor units behaved normally, only the civilians were broken. That continued until I rebooted the server and the issue disappeared.

@NikkoJT

If it's run in an init field, then this is a local argument, since it will definitely run wherever the unit is local.

It'll also run where the unit is not local, which might lead to problems (or maybe it just has no effect; idk)

It works just fine.
First of all, the command takes local args
Second of all, you're not supposed to use it in init fields

I just realized you can do this with the ASLToAGL command. This can be closed.

Try these first:
Verify the game data via Steam.
Make sure your graphics driver is up to data.

Upload your images here. They're only accessible to you on your Discord

@dedmen
Not fully fixed. If the control is in a controlsGroup, it doesn't work properly, it uses the position of its controlsGroup parent, instead of its own absolute position.
In other words, to do the backward selection you have to move the mouse all the way outside of the controls group for it to work (forward selection works fine though):

_disp = findDisplay 46 createDisplay "RscDisplayEmpty";
_grp = _disp ctrlCreate ["RscControlsGroup", -1];
_grp ctrlSetPosition [safeZoneX+0.2*safeZoneW, safeZoneY + 0.2 * safeZoneH, 0.6 * safeZoneW, 0.6 * safeZoneH];
_grp ctrlCommit 0;

@BIS_fnc_KK
This is the same request, so please close it: T153432

In T156218#2155704, @dedmen wrote:

[public] Fixed CEdit Mouse selection not able to select text that is on the left outside of view area

omg please give me a better changelog entry

Did you verify the game cache via Steam?

In T156218#2154163, @dedmen wrote:

Do you know if that is new? As I recently touched exactly that code.