Random unhappiness

[Blodrast]

welcome to the Org, eadeater !
Don't worry too much about that, it is a known and unavoidable phenomenon, and there are two stages to it:

1. when you own roughly 40% of the provinces, your governors start getting bad vices at an accelerated rate. That is more or less bearable and acceptable, depending on how tolerant you are.
2. when you reach 60%, however, all hell breaks loose. You will get countless bad vices (and I mean really bad ones this time, too) to lots of governors and generals, and, consequently, loyalty will decrease throughout your empire. It is in no way money or income related.
By this time you'll have a really hard time making new alliances, and likely you'll be at war with everybody else (which means mostly no trade income, which means you may get in the red with money).
Most important thing to look out for, though, is loyalty in provinces (hold shift to have a quick look at your provinces; green are ok; yellow and red, well...) and in your generals, because civil wars are so much easier to come about at that time...

There are many ways to prevent massive drops in loyalty, though, and here are only some of them:
- build happiness buildings:
Watch Tower + 20
Border Fort + 30
(these two do NOT stack; all others do)

Town Watch / Town Guard /
Town Militia / County Militia + 10
Brothel / Brothel2 / Brothel3 + 10

Church + 20
Monastery + 10
Reliquary + 30
Cathedral + 40

Mosque + 20
Grand Mosque + 40

College of Surgeons + 40

- have a spy and an assassin in each of your provinces
- keep your king in a coastal province and make sure you have unobstructed sea access to all your provinces (i.e., there are no enemy ships in any sea squares that are part of the sea route between your king and one of your provinces).
- never ever assault/attack with your king/only heir on an island (port might get destroyed and he'll be stranded).

Good luck, and enjoy your stay around here !

Edit: Oh yeah, about autotax: original MTW sets autotax such that loyalty stays above 100%. This is good enough for usual rebellions, but not for re-emergences. You need at least 120% for that, and some more than that is helpful to absorb occasional drops (influent king with good virtues dies, heir doesn't have them). Autotax in VI sets the tax such that loyalty is at least 120% (i.e., better than MTW).