Im not sure but as a good guess... Id try right click blank area on desktop - properities - under apperiance header - windows & buttons there is 2 choices Windows XP style or Windows Classic style. Try switching those.
For some reason the above is choice 2.
For some reason I think changeing THEMES is the awnser that may be your simple solution. Id try themes 1st.
Then again I am no expert, I just know that "mouse-over" with-in microsoft picture it 7.0 has that same effect, it blacks out whatever is mouse-over highlighted and it wasnt that way till I changed 1 of the above 2 suggestions. I just decided to live with the blackout since I already know what it is Im after for example I click on crop and the rotate/crop/? extension comes out and what I mouseover (crop) is blacked out lol. Good Luck.