Can you tell us a bit more about your setup? What version of Premiere are you running? How were the titles created? Are they .prtl files from the title tool or maybe PSD files from Photoshop? You didn't say.
Also, what are your export settings? If things look ok while editing then it's likely your export that causing the issue.
Also, can you describe further the details of your timeline. It sounds like you have a title (prtl?) in layer 2 and black video sitting in layer 1 but I suspect that's not right because making the black layer opacity down to 50% fromt here will just show up the 'black nothing' underneath.
And, as an aside, I checked your profile cos I used to work with a chap with the same name. You'll be too young though but I did notice you have the same birthday as me