Ubuntu 12.04 contains error reporting system named Apport that can send error information to Ubuntu center in case that something goes wrong on your system. Debugging program crashes without any automated tools has been pretty time consuming and hard for both developers and users, so that is the main reason why this system exists.
There are many reported issues caused with various reasons displaying the message error:
Sorry, Ubuntu 12.04 has experienced an internal error
If you experience something simillar you can click on "Show Details..." button to see what data it collected. On my system (Acer Aspire One D257 Netbook) this is the issue that used to appear very often:
Sorry Ubuntu 12.04 has experienced an internal error.
If you notice further problems, try restarting the computer.
Unity-music-daemon crashed with SIGSEGV in g_bit_lock()
How to disable Apport error-reporting system in Ubuntu
However, you can disable the error-reporting system following the steps:
1) Run the command
sudo gedit /etc/default/apport
2) Change the value of the "enabled" parameter from "1" to "0"
3) Save changes