https://secure.eicar.org/eicar_com.zip
download this.
scan using avast, click show results…
voila the UI bug appears…
see screenshot
No bug here, using Windows XP SP3
Im too using xp sp3… the grey box appears before u click at it to change options… im using 5.0.545
So you are saying that before you put the cursor on top of the box it appears grey? …or you definetely can NOT access the pull down menu?
i can access it , but before i do so it appears 
and hey dont click it and check whether u too get the same and post
I do not think this is a bug but a feature (you do not have the full resolution until you are ready to go) please see attached jpeg´s
i didnt get the way u got it properly 