Just happened to me this morning. Nothing going on for either character. Both on Skyfire. Two different accounts. One I haven't logged into for a couple of weeks. My merc and my character can attack a mob, but got 'you are too busy to loot right now' when I tried to loot a chest. This was in Steamfont Mts. Logged out and back in, same character and server, could loot then. Killed another mob, couldn't loot it. 'too busy'. Logged out of that account, logged into one as mentioned above not in a couple of weeks. Couldn't buy from broker, said 'you are too busy'. But I could open and read mail, get items in mail. This was in Qeynos. Log parts below. Checked my internet connection, it is fine. I am on 500 megabit Internet/cable modem. Here is the log for one of the characters, the one who could engage in combat, but couldn't loot. (1565977289)[Fri Aug 16 12:41:29 2019] Nerrin Drudge has killed a Bloodhorn enslaver. (1565977289)[Fri Aug 16 12:41:29 2019] Your faction standing with Clan Smokehorn got better. (1565977289)[Fri Aug 16 12:41:29 2019] You gain 189 XP plus 473 XP from bonuses! (1565977289)[Fri Aug 16 12:41:29 2019] You convert 93 experience into AA experience! (1565977289)[Fri Aug 16 12:41:29 2019] You gain 54 XP for defeating the encounter plus 135 XP from bonuses! (1565977289)[Fri Aug 16 12:41:29 2019] You convert 26 experience for defeating the encounter into AA experience! (1565977289)[Fri Aug 16 12:41:29 2019] Too little too late... Your target is already dead. (1565977289)[Fri Aug 16 12:41:29 2019] Nerrin Drudge's Fond Memories refreshes Nerrin Drudge for 85 mana points. (1565977290)[Fri Aug 16 12:41:30 2019] Nerrin Drudge's Fond Memories refreshes Nerrin Drudge for 42 mana points. (1565977292)[Fri Aug 16 12:41:32 2019] Nerrin Drudge's Fond Memories refreshes Nerrin Drudge for 42 mana points. (1565977293)[Fri Aug 16 12:41:33 2019] You are too busy to loot right now. (1565977293)[Fri Aug 16 12:41:33 2019] Nerrin Drudge's Fond Memories refreshes Nerrin Drudge for 21 mana points. (1565977295)[Fri Aug 16 12:41:35 2019] You are too busy to loot right now. (1565977299)[Fri Aug 16 12:41:39 2019] You are too busy to loot right now. (1565977305)[Fri Aug 16 12:41:45 2019] You are too busy to loot right now. (1565977313)[Fri Aug 16 12:41:53 2019] You are too busy to loot right now. (1565977314)[Fri Aug 16 12:41:54 2019] You are too busy to loot right now. (1565977315)[Fri Aug 16 12:41:55 2019] You are too busy to loot right now. (1565977315)[Fri Aug 16 12:41:55 2019] You are too busy to loot right now. (1565977316)[Fri Aug 16 12:41:56 2019] You are too busy to loot right now. (1565977317)[Fri Aug 16 12:41:57 2019] You are too busy to loot right now. (1565977317)[Fri Aug 16 12:41:57 2019] You are too busy to loot right now. (1565977318)[Fri Aug 16 12:41:58 2019] You are too busy to loot right now. (1565977330)[Fri Aug 16 12:42:10 2019] You are too busy to loot right now. (1565977331)[Fri Aug 16 12:42:11 2019] You are too busy to loot right now. (1565977335)[Fri Aug 16 12:42:15 2019] Looting restrictions for corpse of a Bloodhorn enslaver will be removed in 1 minute and 13 seconds. (1565977341)[Fri Aug 16 12:42:21 2019] You are too busy to loot right now. (1565977353)[Fri Aug 16 12:42:33 2019] You are too busy to loot right now. (1565977359)[Fri Aug 16 12:42:39 2019] Too little too late... Your target is already dead. (1565977362)[Fri Aug 16 12:42:42 2019] You are too busy to loot right now. (1565977368)[Fri Aug 16 12:42:48 2019] Looting restrictions for corpse of a Bloodhorn enslaver will be removed in 40 seconds. (1565977398)[Fri Aug 16 12:43:18 2019] You are too busy to loot right now. (1565977411)[Fri Aug 16 12:43:31 2019] You start fighting. (1565977411)[Fri Aug 16 12:43:31 2019] YOU hit a mountain lion for a critical of 912 crushing damage. (1565977412)[Fri Aug 16 12:43:32 2019] Nerrin Drudge's Arcane Bewilderment hits a mountain lion for 936 magic damage. (1565977412)[Fri Aug 16 12:43:32 2019] Nerrin Drudge's Arcane Bewilderment reduces THEIR hate position with a mountain lion for 1 position. (1565977412)[Fri Aug 16 12:43:32 2019] Nerrin Drudge hits a mountain lion for 1393 crushing damage. (1565977412)[Fri Aug 16 12:43:32 2019] Nerrin Drudge multi attacks a mountain lion for a critical of 2346 crushing damage. (1565977413)[Fri Aug 16 12:43:33 2019] Nerrin Drudge tries to crush a mountain lion, but a mountain lion parries. (1565977413)[Fri Aug 16 12:43:33 2019] Nerrin Drudge tries to crush a mountain lion, but their multi attack misses. (1565977413)[Fri Aug 16 12:43:33 2019] a mountain lion hits Nerrin Drudge for 155 slashing damage. (1565977413)[Fri Aug 16 12:43:33 2019] Nerrin Drudge's Linked Pain reduces THEIR hate position with a mountain lion for 1 position. (1565977414)[Fri Aug 16 12:43:34 2019] Nerrin Drudge hits a mountain lion for 1249 crushing damage. (1565977414)[Fri Aug 16 12:43:34 2019] You stop fighting. (1565977414)[Fri Aug 16 12:43:34 2019] Nerrin Drudge has killed a mountain lion. (1565977414)[Fri Aug 16 12:43:34 2019] You gain 165 XP plus 413 XP from bonuses! (1565977414)[Fri Aug 16 12:43:34 2019] You convert 81 experience into AA experience! (1565977414)[Fri Aug 16 12:43:34 2019] You gain 47 XP for defeating the encounter plus 118 XP from bonuses! (1565977414)[Fri Aug 16 12:43:34 2019] You convert 23 experience for defeating the encounter into AA experience! (1565977418)[Fri Aug 16 12:43:38 2019] You are too busy to loot right now. And here is the one for unable to trade. (1565979462)[Fri Aug 16 13:17:42 2019] Message of the Day: Welcome to Norrath! (1565979483)[Fri Aug 16 13:18:03 2019] \aNPC 82814 a Qeynos resident:a Qeynos resident\/a says, "I only dream of short days and long nights in the tavern." (1565979518)[Fri Aug 16 13:18:38 2019] \aNPC 88103 an awestruck Qeynos resident:an awestruck Qeynos resident\/a says, "I can look up at Luclin and know I will never see Kerafyrm's shadow again." (1565979522)[Fri Aug 16 13:18:42 2019] You are too busy to trade at this time. (1565979529)[Fri Aug 16 13:18:49 2019] You are too busy to trade at this time.
This happens once in a while, it also happens with the mail, the broker, and the merchants. I would try sending a private forum message to Dreamweaver and Gninja. Dreamweaver can forward your thread to someone who can fix it or Gninja can fix it.
I would just /petition, that puts it right in the CSR's work queue. No need to send it elsewhere first.
Alt-Tab wouldn't make a difference. Somewhere in Options there's a checkbox that forces any off-screen game windows back on-screen.
Hitting Esc or using Sigrdrifa's Enter to Accept so you can just hit Enter may also close an off-screen window.