trojan - the returning virus

Alright so i have had a problem with this virus in particular, the first time I got this threat it shut down my microsoft security essentials so i could not scan. it also shut down my anti-malware and internet browser. I have had a professional in to help me with this issue and he had gotten rid of it. He was skeptical and said even though he cleaned my pc and got rid of the threats i might be better off just reformatting, so there goes $150 to be told something i should have just done :grin: . He also installed a better anti-virus (Vipre antivirus) and some better anti-malware for me.

I had gone about 2 weeks without issues then the same trojan returned onto my pc... the thing is i dont go on many sites just facebook,youtube and google. I was just searching music lyrics on google at the time and the link i clicked on was for a site i have been familiar with for a while with no problems. i managed to get the anti-virus to scan and it detected 1 threat..from what i remember it was "trojan.win32.generic!BT". i immediately made sure it was quarantined and deleted it from my computer.. that did nothing. Anything i can do? or am i just better off backing up my files and reformatting... Also will reformatting do anything ? because the virus was completely gone from my computer but it still managed to come back..

thanks for feedbacks.