After questions on how to spot if a pc has a virus the inevitable questions follow "My PC is infected how do I remove the virus" or "I've found a Virus my antivirus can't remove it" . Don't panic if this happens although its true some virus can be very destructive and be a problem to remove the vast majority are easy enough to remove without any lasting damage.
Here are the steps I would advise following
Isolate the Infection
If you machine is connected to a network or the Internet disconnect it and do not attach it back until you are sure your machine is clean, this will not only prevent the virus/worm or trojan spreading but also stop your computer becoming re infected until you have it properly secured.
Crackers pride themselves on their ability
to create havoc to other users, and do not
care how many people they affect.
Inform other people
If you can connect to the internet from another computer we would advise informing others that may need to know, for example you may know that the virus came from an email attachment or that it may have spread from your machine via email, so inform anyone in your address book that they should check there machines out. If you run a network make sure everyone is aware there is an infection that is being removed and not to open any email attachments or attach any new pc's or laptops until the threat has been removed.
Identify and Remove the Virus
Use your antivirus software to scan all of your machines disks and files for a virus in a lot of cases the antivirus program will eradicate the virus for you. If you machine does not have any software install some or get updates from the internet using a non infected machine and scan.
Your anti virus software should give you the name of the virus if it has any problems in removing the infection a basic search using the virus name should give you any information or steps you need to take. Stick to known web sites like microsoft, symantec, MacAfee, f-secure or similar where they often have virus removal tools specific to the infection your machine has, download and follow there instructions
If the infection stops you from running virus defense software they you can often run these from a CD or follow manual steps in checking and removing virus. You can also contact a antivirus vendor for advice and they can take file analysis or talk you through what to do.
If you run system restore on your computer then you could go in to this and roll back your system to a date previous to the infection and then follow the stop re infection steps.
If all else fails as a last resort reinstall your machine - this is not something that everyone is comfortable in doing so you may wish to seek help and remember you will loose any data or programs when you do this. However many computer users now use programs like disk image or ghost to take backups of the systems and keep there data backed up, if you have done this then reinstalling is quick and will return you to a fully working clean machine.
Stop any Re infections in the future
Basically this is done by following the same steps in the how to protect your computer from a virus. Keeping everything up to date security wise along with backing anything up.
- Back up critical files on a regular basis
- Visit Microsoft Update and turn on Automatic Updates.
- Install a good antivirus software and keep it current.
- Use a firewall on your computer
- Never open an e-mail attachment from someone you don't know
- Be aware attachments from someone you do know may be infected without there knowledge always save and scan before opening.
- Make a disk image or ghost your machine so if you ever need to reinstall its a lot quicker to get your machine back up and running without suffering the loss of crucial data.