Is this a computer virus? Details inside?

Recently I have noticed that whenever I look something up, usually in Bing but also in Google, whenever I try to go back there are several intermediate steps that have appeared between whatever site I am on and the search engine.
Many times it is something containing the word doubleclick or admanager.
My computer has been acting up lately but I regularly run adaware, spybot and mssecurity essentials and they have not come up with anything specific. They are all up to date.
Any ideas? Is it viral? Any suggestions on how to get it to stop