Using XP, BitDefender, Spybot S&D and AVG anti-spyware.

I run BitDefender and it tells me no viruses.
I then run Spybot and it tells me no spyware.
I then run AVG and while it is telling me no spyware, I get spyware alerts from
BitDender, that it has blocked multiple infections of Adware. I look in BitDefender Quarantine, to delete, and nothing is there.

Each time I do the above, I get the same results, i.e., no viruses, no spyware, no spyware, but multiple spyware alerts.

Do I have spyware? If so, why doesn't Spybot or AVG confirm it? If BitDefender has blocked it, why is it not in Quarantine?