That sounds like Dashboard.
You can change settings, so you don't accidentally trigger dashboard widgets.
Go to System Preferences, then the Mission Control pane.
Un-Check the box "show Dashboard as a Space". That will assure that if dashboard DOES appear, it will simply show the dashboard widgets as a popup on the existing screen, not changing to a different screen space.
And, you can simply click on the background, and the widgets move off the screen immediately (or press escape, whichever is more convenient for you)
You can also turn off the keyboard controls that trigger dashboard:
Click the dropdown next to "Show Dashboard", then choose the (-). That means that no standard key press will trigger it.
Then, press the Hot Corners button. Make sure that there are no corners that trigger Dashboard.
That means that you will not trigger Dashboard inadvertantly by moving your mouse cursor into a corner of the screen.
While you are there, you may find that OTHER options will help you work more easily by enabling screen corners for different functions.