N4 battery drain / power loss due to "Media server"

Noticed yesterday (albeit after a big GTA III sesh) that my battery seemed to have run down suspiciously quickly
Checked in Settings>Battery and saw that "Media Server" was responsible for 52% of the power usage, with GTA III accounting for rather less (20 something % IIRC)
Was a bit confused by this as I'd not been listening to music, watching videos recently
Googled "Nexus 4 media server" and found a lot of reports of problems like this, with a suggestion that this jellybean build doesn't shut down things like Google Music as it should.  So I went to shut down all media services and remembered I don't have Google Music installed (not available here in Ireland)
Others have blamed games for weighing heavy on Media Server, so I shut down GTA III but still the Media Server usage increased
Then I noticed I had 20 odd Chrome tabs open, probably one or two with Youtube pages open
I closed the lot and that seemed to put paid to the problem

Except I just checked media server again and it's back up to 15% of total power consumption, with no Youtube or Chrome tabs open, no media having been played (aside from my alarm this morning - could it be that?).  I have played GTA III since for a few mins, but just checked whether this seemed to be the culprit as follows - noted the Media Server "CPU Total" and "Keep Awake" times, opened GTA III and then rechecked "CPU Total" and "Keep Awake" and found neither had increased.

Anyone else noticed this or have any ideas?  I will stick Better Battery Stats on this evening and see if I can figure out what's afoot...

EDIT - oops - meant to say, I'm on stock 4.2.1 ROM, build JOP40D, Bootloader unlocked and Rooted

Edited by The Soup Thief, 03 January 2013 - 12:55 PM.

Got a bit annoyed with this last evening after reading around. Also wanted a de-odexed rom so i could add some tweaks. I downloaded Paul's Jr 5 (along with Franco Kernel), flashed them this morning and lo and behold, no more Media Server drain. In fact it's battery usage was pretty significant at the point at which I flashed the MCR - checking battery stats a few times this morning it's clear that Media Server's not been active since the flash, with it consuming no further power (I have not charged the battery since the flash, so the residual consumption from when it was on the stock ROM still appears in my stats, if you follow my meaning)
Anyway, take home message seems to be, if you have this problem on the stock firmware, flash the MCR. It's a bit of a shame to be honest - I quite liked the idea of using pure Nexus firmware, though happily Paul's ROM only seems to have tweaks where you want them!