Because trojans are a very common type of malware that is known to practically all web surfers, it is clear how hard it is to answer the question "how do i remove a trojan virus from my computer?"
A trojan virus makes a PC user think that it is a beneficial Windows application. Thus, trojans often masquerade as screensavers, packages of video codecs, tray clocks, weather forecast software, messengers, etc. Another major source of trojans is all kinds of illegal programs, cracks and keygens. It is a common practice to include trojans into free antivirus software distributed via peer-to-peer networks (e.g. torrents). This is especially dangerous for end-users because antivirus program cannot detect a trojan before the installation finishes and all updates are downloaded, thus the use of free antivirus software downloaded from suspicious websites or sources imposes a great risk on personal computers.
Moreover, one of the most difficult things in PC maintenance is to remove trojan virus from a PC where software of a suspicious origin has been installed.
TOP-10 Internet Threats (July, 2008), by: BitDefender, www.bitdefender.com
While it is possible to remove trojan virus manually, the set of steps involved in PC cleaning requires a decent level of computer experience. There's a need to indentify the type of malware, to locate infected or harmful files and registry entries, to download the tools that will help to remove trojan virus.
A common practice implies the use of special software, commonly referred to as 'trojan removers'. It is however important to point out that this type of programs makes a considerable part of antispyware software market, which is a big incentive for some programmers to make quick money by releasing trojan removers with mediocre scanning engines, poor algorithms, and no support.
Therefore I feel it's necessary to warn you, the readers of this hub, that the decision about preferable trojan remover should be done after at least basic research of the available programs. User feedback and reviews are important sources of information, though the quality of reviews of trojan removers often leaves much to be desired.
NOTE: Every program recommended in this hub is 100% safe to use. I give as detailed descriptions as possible, with an accent on vital features not to be found in competitors' software. Same applies to any download links given below.
Some folks prefer to remove trojan virus for free. I myself am a big fan of freeware tools, but there's a big problem here. Some developers of scam software promote their products as free trojan virus removers, to entice web surfers into downloading and installing them. However, such free trojan removers are often more dangerous than trojans. Even scanning of executable files by antivirus programs may show them as clean. This is yet another reason why I advise to make some research before downloading and installing any software that promises to help to remove trojan virus.
Online scanners are an absolutely safe and free way to remove trojan virus. All major antivirus software makers offer online virus scanners on their websites, and these services are available for everybody enjoying a stable Internet connection. Not all of the scanners have same detection rate, and they differ in types of malware they're able to remove.
For trojan viruses involved in the distribution of rogue security programs, there are special tools developed by volunteers. These tools have a very specific targeting and are meant to fight either certain trojans, or a range of malware. Usually such tools are created because major antivirus and antispyware companies fail to address new threats quickly. This happens either due to bugs in scan engines, or requires significant updates.
Command-line anti-malware scaners present another way to remove trojan virus for free. Sadly, I was able to find only two completely free and available scanners: TrendMicro SysClean and a-squared anti-malware command-line scanner. The latter is suitable for PC users with intermediate experience, while TrendMicro software is aimed at advanced users or system administrators.
source: hubpages.com