maybe i must set something for my graphic card ati catalyst
I don't think so, unless I've done it accidentally. (ATI here as well, and an old one at that).
Make sure in OD config / General / "Performance Options" button you have "Optimize for performace" selected.
Also, try unloading Object Dock (right-click on OD systray icon) and re-starting it, see if after re-starting it works right.
Are you running any other graphics-intensive software at any point that might fight with it (Dvd players, videos, software aquariums, games, ATI MMC stuff)?
Is the dock trying to open up on top of any other graphics object (Sysmetrix objects, DTX objects)?