xbox 360 achievement problems

[~Ethan~]

Don't know if there is anyone here that will know but I have to try.
Ok so here's the situation: I'm playing borderlands and I start getting these achievements that don't show up anywhere. Like I'll get one that's called "Made In Fyrestone" worth I think 5G, everytime I complete any quest. And now I'm getting "12 Days Of Pandora" 30G when I kill anything, and it'll pop up for each enemy I kill, i.e. 3 simultanious kills = 3 of the same achievement.
I've connected to xbox live and got the latest update and that did fix anything. The only thing I can think of is that maybe it's some kind of bug, but how do I fix it?

[KeithBMI]

The only thing I can think of is going into the system settings and clearing the cache.