This is the first time I've seen this beahviour and since it was immediately after installing a mod I was under the impression that was the cause.
I've since been told this is a problem with native SS rather than any specific mod.
Ref:
Found something that might need looking at....
Docked at Macau in Magec and got this: http://i12.photobucket.com/albums/a224/Tifi78/iamerror_zpsbtpke127.png (http://i12.photobucket.com/albums/a224/Tifi78/iamerror_zpsbtpke127.png)
The superchill port music was playing, but no menu elements appeared and there was no response at all from the game and it had to be process killed from taskman.
And this is the log that was generated.
Spoiler
4928174 [Thread-11] INFO sound.O - Creating streaming player for music with id [TiandongMarketInteractionFriendly.ogg]
4928185 [Thread-11] INFO sound.OooOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOOOOOO - Playing music with id [TiandongMarketInteractionFriendly.ogg]
4938478 [Thread-5] INFO com.fs.starfarer.api.impl.campaign.events.TradeInfoUpdateEvent - Picking market updates
4938478 [Thread-5] INFO com.fs.starfarer.api.impl.campaign.events.TradeInfoUpdateEvent - Adding Hand Weapons(Macau)
4938496 [Thread-5] WARN com.fs.starfarer.campaign.rules.oOOO - Problem with command of class com.fs.starfarer.api.impl.campaign.rulecmd.OpenCoreTab: null
java.lang.IllegalStateException
at java.util.ArrayList$Itr.remove(Unknown Source)
at com.fs.starfarer.campaign.comms.PlayerTransactionLineItemData.øÕ0000(Unknown Source)
at com.fs.starfarer.campaign.comms.IntelTabData.performCleanup(Unknown Source)
at com.fs.starfarer.campaign.CampaignEngine.super(Unknown Source)
at com.fs.starfarer.campaign.CampaignEngine.reportPlayerOpenedMarket(Unknown Source)
at com.fs.starfarer.ui.D.I.<init>(Unknown Source)
at com.fs.starfarer.ui.D.O00O.showCoreInternal(Unknown Source)
at com.fs.starfarer.ui.D.O00O.showCore(Unknown Source)
at com.fs.starfarer.api.impl.campaign.rulecmd.OpenCoreTab.execute(OpenCoreTab.java:39)
at com.fs.starfarer.campaign.rules.oOOO.execute(Unknown Source)
at com.fs.starfarer.campaign.rules.O0OO.runScript(Unknown Source)
at com.fs.starfarer.api.impl.campaign.rulecmd.FireBest.applyRule(FireBest.java:97)
at com.fs.starfarer.api.impl.campaign.rulecmd.FireBest.execute(FireBest.java:47)
at com.fs.starfarer.api.impl.campaign.rulecmd.FireBest.fire(FireBest.java:53)
at com.fs.starfarer.api.impl.campaign.RuleBasedInteractionDialogPluginImpl.fireBes t(RuleBasedInteractionDialogPluginImpl.java:110)
at com.fs.starfarer.api.impl.campaign.RuleBasedInteractionDialogPluginImpl.optionS elected(RuleBasedInteractionDialogPluginImpl.java:142)
at com.fs.starfarer.ui.D.O00O$1.o00000(Unknown Source)
at com.fs.starfarer.ui.D.super.actionPerformed(Unknown Source)
at com.fs.starfarer.ui.thisnew.super(Unknown Source)
at com.fs.starfarer.ui.H.processInput(Unknown Source)
at com.fs.starfarer.ui.V.o00000(Unknown Source)
at com.fs.starfarer.new.Òôo000(Unknown Source)
at com.fs.oOOO.oOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO.Ò00000(Unknown Source)
at com.fs.starfarer.combat.D.o00000(Unknown Source)
at com.fs.starfarer.StarfarerLauncher$2.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)