I've seen this most frequently if you are connected via HDMI cable.
Two things to check:
First, check your monitor. You may have a setting to select between AV and PC. Make sure it's set to PC.
If that doesn't work, go into Catalyst Control Center, and under "My Digital Flat Panels," check "Scaling Options (Digital Flat-Panel)" and make sure the Underscan -- Overscan control is set to 0 -- all the way to the right.
Two things to check:
First, check your monitor. You may have a setting to select between AV and PC. Make sure it's set to PC.
If that doesn't work, go into Catalyst Control Center, and under "My Digital Flat Panels," check "Scaling Options (Digital Flat-Panel)" and make sure the Underscan -- Overscan control is set to 0 -- all the way to the right.