"err" message

[BodieInSD]

I recently got a new (I have never seen it before in TTW or 'plain' FNV) "glitch" that I am curious about.
When looting the (locked) footlocker near the entrance of the Deathclaw Sanctuary I got an "err" (just err, not error) message in the top left corner of the screen. I could not close the locker to get back to the game, and no loot was listed in the right-hand column though a weight of 40-some pounds was listed on the footlocker side (I use Vanilla UI-Plus, not sure if that is shown with the vanilla FNV UI), and I could not take the materials in the box. I was able to use "esc" to go to the pause menu and load the saved game.
The same thing happened again. I reloaded again and simply picked the lock and left it unopened (my LStewies tweaks settings stops containers from automatically opening after picking a lock), and then went to the nearby dead mercenary to loot him and got the same "err" in the top left corner when doing so.
Frustrated I simply quit and was going to save a screenshot of it to post here the next day. When loading the (same) saved game the next day, it worked fine - no "err" message, and no problems looting either the footlocker or the dead merc. Since it "corrected" itself, I can't really call this a "bug" with the TTW mod, so much as "glitch". And likely a glitch with my system or setup.
Can anyone give me a hint/clue/answer as to what this was? I can't replicate it and have never seen it (or even heard of it) before. Many thanks...

[Laclongquan]

List your load order please.

[BodieInSD]

List your load order please.

SpoilerShow

0 0 FalloutNV.esm
1 1 DeadMoney.esm
2 2 HonestHearts.esm
3 3 OldWorldBlues.esm
4 4 LonesomeRoad.esm
5 5 GunRunnersArsenal.esm
6 6 Fallout3.esm
7 7 Anchorage.esm
8 8 ThePitt.esm
9 9 BrokenSteel.esm
10 a PointLookout.esm
11 b Zeta.esm
12 c CaravanPack.esm
13 d ClassicPack.esm
14 e MercenaryPack.esm
15 f TribalPack.esm
16 10 TaleOfTwoWastelands.esm
17 11 YUPTTW.esm
18 12 Functional Post Game Ending.esm
19 13 Regulators.esm
20 14 AnotherInteriorMod.esm
21 15 Expanded Megaton House - TTW.esp
22 16 A Trail of Crumbs.esm
23 17 ISControl.esm
24 18 Two Wastelands Redesigned.esm
25 19 ClimateControl.esm
26 1a B42Inspect.esp
27 1b Uncut Wasteland.esp
28 1c sawyerbatty.esp
29 1d Mojave Raiders.esp
30 1e Mojave Wildlife (FO3-Style).esp
31 1f DC Arsenal 2.esp
32 20 Functional Post Game Ending - Uncut Wasteland Patch.esp
33 21 Benny Humbles You and Steals Your Stuff.esp
34 22 Better ArmourRepairKits (x3).esp
35 23 CPI Icons.esp
36 24 Dogmeat Leather Armor and Backpack.esp
37 25 FirstAidNVSE.esp
38 26 FruitJuices.esp
39 27 JIP Improved Recipe Menu.esp
40 28 ttw - mojave raiders patch.esp
Mojave Raiders - 22LR Varmint Rifle.esp
41 29 Victors Shack GSPH.esp
42 2a uncut wasteland - ttw patch.esp
43 2b zz_Sunglasses.esp
44 2c Mojave Wildlife - TTW Patch.esp
45 2d MojaveImportsTTW.esp
46 2e R.A.C.E. Station.esp
47 2f Simple Natural Weathers for TTW.esp
48 30 The Mod Configuration Menu.esp
49 31 TTW Armored Wasteland.esp
50 32 TTW Ratslayer DC.esp
51 33 TWR + SawyerBatty.esp
52 34 TWR Uncut Patch.esp
53 35 Vanilla UI Plus.esp
54 36 zzAlcoholFixes.esp
55 37 Mojave Arsenal.esp

This is just a cut/paste from LOOT (only used to sort MO2's load order), hope that is sufficient