Bitdefender not detecting Tone

So first thing that tipped me off to malware on my PC was that my Google searches started getting hijacked to Bing. When I would open Chrome it would stay open for about 30 seconds, then the window would close and reopen a few seconds later. I did a little research and downloaded Bitdefender Anti-virus Plus. Did a full computer scan, caught a couple things, not the major one though, I did notice in the logs though that it was detecting re-direct attempts by something called Tone.exe. What puzzles me is that Bitdefender didn’t catch it and remove it in the full scan. Does Bitdefender suck, am I using it wrong, do I need to make adjustments, is Tone just particularly good at hiding from scans? And how can I get a deep clean of removing ALL the malware from my PC(which i hoped Bitdefenderwould do)? Recommendations? Thanks very much in advance!