I recommend AVG antivirus. It is good and it is free, and seems to work on almost all configurations. Relying on an on-line scanner as you AV will not protect you from getting malware, only identify or remove it; a resident, updated AV that scans downloads is an absolute must for any user.
Whichever application you decide to use, besure the definitions are current by updating it, then run it and see what it finds. I would also suggest you download, update, and run a good spyware removal applications, such as Spybot Search and Destroy and/or AdAware.
I have no idea what the Stinger program is or does. Here is a link to various sources about Qhost:http://www.virus-trojaner.de/virus-trojaner/Qhost.php
You need to take active measures to get it off your system.
I have searched several databases, and none of the mention citi.exe. This may well be a trojan or some other malware. Maybe someone else can come up with more on this.