I am using ATI Radeon 4890,but I solved the colour box promblem by Nvidia method.(XD)
Although HBAO is for Nvidia card,it still related to ATI.(lol)
HBAO,is usually turned on.
VSYNC,is sometimes turend on.(For example,you need to both of them turned on in Africa Harbour and Atxxxx Desert)
The problem of weird colour box mainly is caused by graphic settings(High,low,medium).
Therefore,you need to turn one of a setting low(You have already in the game,press ESC for Opition),then back to the game,then back to the Opition,turned one of a setting high.Each of the setting,you need to turned high.
If you have the problem of some shine weapons,shine water/skys become black,
you need to turn on/off HBAO or VSYNC.