The bug is described here:
http://www.elderscrolls.com/forums/index.php?showtopic=293533
Here is what the first post says:
I looked around before posting and didn't see any threads about this, so if it's already been mentioned my apologies. I just figured I'd give everyone fair warning.
I didn't even realize I was affected by this bug until 7 hours of gametime after I completed that quest. My Mercantile skill is still stuck at 21 and it hasn't went up since . There's a few fixes discussed in that thread, but they're dodgy hacks at best. Couple this with a bug that doesn't allow me to fast travel anymore and I'm about ready to unsintall this game. I was having so much fun with it too .
http://www.elderscrolls.com/forums/index.php?showtopic=293533
Here is what the first post says:
The no spoilers bug description:
There are a certain few quests that provide a certain kind of reward. This certain kind of reward causes a skill to never be able to learn or advance moving forward from that point. The skill is 'stuck' if you will. I have spent a couple of hours making sure there was no way around it except for not completing the quest. Unfortunately, I have no workaround. My digging into the quests in the construction set reveals a bug that needs developer attention. The only work-around in the construction set is to alter the reward to not be the certain special kind. Not a big deal to actually perform this mod, but a bummer in removing something interesting.
Spoiler description additions - skip if you understood the above
There are quests (including Ftrs Guild rats, rescuing a girl, and a few more) that give as a reward levels up in a skill. The rescue a girl quest gives a boost of 5 levels in Mercantile. Afterwards, the Mercantile skill is forever stuck. I found no condition that I could get the Mercantile skill to be unstuck after receiving my reward. It has nothing to do with leveling up, sleeping, stat values or anything else under player control. There is a call within a number of scripts (ModPCSkill) that itself is not a script. That would indicate internal game code that modders don't have access to.
I looked around before posting and didn't see any threads about this, so if it's already been mentioned my apologies. I just figured I'd give everyone fair warning.
I didn't even realize I was affected by this bug until 7 hours of gametime after I completed that quest. My Mercantile skill is still stuck at 21 and it hasn't went up since . There's a few fixes discussed in that thread, but they're dodgy hacks at best. Couple this with a bug that doesn't allow me to fast travel anymore and I'm about ready to unsintall this game. I was having so much fun with it too .