Thanks for your comments so far. If anyone has any other ideas as to what the problem could be, I'd appreciate it greatly!
So, after searching everything on my browser, sorting through add-ons, and asking family members about possible ad blocking programs we might have installed, I couldn't find anything that caused this problem. I eventually upgraded our browser from Internet Explorer 8 to version 9, and the problem still persisted!
I must admit, it is very mind boggling. I'll have to keep trying different things to see if I can find a solution.