Hello 
 
Okay looking at the description of how the ad window looks like I'd say it's definitely some sort of malware that has been installed on your PC.  I suggest you use something that can check and help you remove this type of stuff.  I just learned from my brother about Malwarebyte yesterday but I haven't really used it so can't provide any comments on how good or bad it is but he was able to fix a laptop that is in a much more worst shape than yours.  It does have a free version you can use for 14 days before you can decide if it's good enough to buy. 
 
Titus 
		
	
		
		
		
		
			
		
		
		
		
	
		
		
	
	
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