What does this symbol mean on start-up?

OK i was messing around with my laptop the other day and now when I start it up it come with an black screen and the the symbol ^@^@^@
laptop: hp mini 110
OS: Joli os
Any help would be helpful
Thanks,

Trbjr

Did you try to install linux?

Define "messing around". Were you messing around in the terminal entering a bunch of commands? 
If I were you, I would just reinstall the OS and go from there. 

Assuming you did not mean to re-partition your hard drive?

"Joli OS is an Ubuntu-based Linux distribution. It is geared towards extreme user-friendliness so that any computer user can install it with just one click. Besides the standard ISO image, the distribution is also provided as a Windows executable file which can re-size an existing Windows partition and install Joli OS as an alternative operating system." Source: http://distrowatch.com/table.php?distribution=jolios

Re-format, re-install preferred OS

Some motherboards have a built-in linux distro, sometimes hidden. Asus used to do that quite a bit, maybe HP did something similar. After the "runs better on windows"-deal with Microsoft to not deliver linux on netbooks and laptops in 2009, these distros did not go away, they were just hidden from the user's sight. It's actually possible with quite a few motherboards to hack into the linux distro that is installed on the motherboard and take over the computer entirely, even on several desktop boards. Maybe there is something like that on your netbook, and you've just discovered how to get to it.

If you get a prompt, you can start the GUI shell by typing "startx" and hitting enter. Some boards have the linux distro locked in user level and on a chip on the board instead of on peripheral storage. Other systems have a linux partition on the hard drive the system came with. Asus netbooks and laptops used to have a dedicated start button to start up the netbooks in linux instead of windows.