Am going to assume it's not hardware/driver problem.,has it always done this?,or have you just recently installed CLoD for the first time?..,I would check the usuall suspects.,
1. clear out the cache folder if you haven't already.,let it rebuild the shader files. @
C:\Users\you\Documents\1C SoftClub\il-2 sturmovik cliffs of dover\cache
and since your graphic card is ATI.,i do believe you have to delete Ubisoft intro video. Check here for more info.
http://forum.1cpublishing.eu/showthread.php?t=29004