The same thing happens when i try to adjust my lcd brightness. The reason is probably because you adjusted it in another app like the t-mobile app or something else.

 

I had the same problem with the LCD brightness but i took the battery out of the running phone and and the problem din occur anymore

 

When the "notification" sound plays and you don't have a text it is because the system was alerting you to something. Plugging/unplugging the charger, sd card unmounting/remounting.

The sd card mounting/unmounting and getting corrupted is a problem with the BH2 when using the sd card that came with the phone. If you are having this problem you can buy a better quality sd card and most likely solve it. Mist of us swear by Kingston brand for memory.