Does the computer run slowly? Do all the applications and files work?
Go to your system preferences.
Click on 'Users and Groups'
Click on your account (I assume it has your name and administrative privileges.)
Click on 'Log in items'
See if there is an application you do not recognize.
Write its name down exactly as it is written.
Select the item.
Hit the minus key.
Quit from system preferences.
Restart your computer.
See if the strange image disappears.
Let me know what happens and I can give you further steps if you want to restore the item or remove it entirely from your computer.
I've never seen this before.
Do you have antivirus software and is it update? If so run a scan.