why do computers have virisis?
92561
A computer that is not constantly kept secure and up to date is vulnerable to many different attacks. The most common is an automated hacking attack called a worm. Worms hack into computers that have security vulnerabilities, then use those computers as slaves to hack into every other computer on the network. Whenever you are vulnerable to a worm, you are also vulnerable to a manual hacking attempt. \n\nThe main objective of a worm or hacking attempt is usually to hack into more computers. It appears to anyone on the network that the infected computer is attempting to hack into their computer directly. ISD takes all hacking attempts seriously and will block network access for any computer that appears to be attempting to hack into other computers. ISD can only enable these computers after the worm or problem is fully removed and all relevant security patches have been applied. \n\nThere are other serious implications of hacks and worms. Some attacks aim to steal passwords, software license keys, and credit card numbers. Some attacks turn the computer into a slave computer of the hacker, possibly filling up the hard drive and utilizing your entire network connection.
58164
We're getting closer to this kind of solution.  Host-based Intrusion Prevention Systems (HIPS) are able to identify virus-like behavior and prevent it.  This includes things like deleting files, writing files to certain folders, copying files, performing certain actions in memory, etc.  HIPS can also block certain types of network traffic.  This is an emerging technology; and it's far from perfect.  But it's a move in the right direction.  Some day our computers will recognize attack behavior and kill the malware causing it.
609652
each virus is different, so you'd need to know which one it was...or know in-depth how your os works (and that is a book, not a post at yahoo answers)
947465
Then your computer will get infected. That's why you have to use a good antivirus program and when it finds an infected file delete that file!  Here you have some good and free antivirus programs:\nhttp://askcomputerexpert.ws43.com/download/
59116
Most people create viruses for a challenge to themselves to see if they can get by firewalls, anti-virus, and other security settings.  Some do it just to be a pain.  Others do it for malicious reasons like stealing passwords and personal information from your PC!
301248
When u install an anti virus software, it resides in the primary memory(RAM). So the RAM space gets reduced & hence the system slows down.\n\nJust imagine u build a divider too wide on a road, obviously the road width decreases & the traffic moves slowly than before. Same is the case here.
1040546
the virus likes to mutate. so even if they did have one.. it wouldn't work for very long
801358
It's not a disaster\nIt just slows down your computer\nIt's impossible it cannot be removed.\nTry to shut the virusscanner down, and then remove it.
851020
The registry is like the bloodvessles in your body and the keys are the blood. Some are small and can be eliminated without too much trouble, others are absolutely vital and deletion will kill your whole system.\n\nHow do you tell the difference? You probably can't. Get an expert or go to a virus site like panda or macaffe and follow the instructions they give you PRECISELY to remove an infection.\n\nGood luck!
616638
have you ran any computer scans to find and possibly remove small viruses?
924653
Antivirus programs are far from perfect. They're known for misidentifying files as viruses.
930021
Reason #55,907 that I run http://pclinuxos.com  \n\nAll the 'drivers' resources are included, \n(except for a few braindead peripherals that only can be used with Microsoft), that penalize speed, and commit consumer fraud... \n\nand, all the "114,000 Microsoft Virus Definitions" are excluded!
122486
If it is a boot sector virus you will still have it. They are somewhat rare these days because most viruses are written to exploit security flaws in microsoft software these days.\n\nI think that formatting it will be good enough to remove it.
807192
I know why. Your computer is not infected with virus. Its normal. You need to speed up your computer by going to the start menu, click on all programs, click on accessories, then on disk defragment. When a window pop up click on defragment. This will make your computer run faster and you will see better results from your computer.
204144
Neither program has a very high virus detection rate. Expect them to not detect about 10% of all viruses. Some paid solutions such as Kaspersky miss less than one half of one percent.\n\nThat being said I use Avast (you can't beat the price). And it uses about 15 to 18 mb on my comp.
87698
It isn't cleaned or removed because it isn't a virus. It's a system file, an index of the files in that folder, like a table of contents for the computer to read.
22961
I would start the answer by the famous quote, "Why do computers get viruses. They're little boxes. They shouldn't." ~ Janelle\n\na virus is a self-replicating program that spreads by inserting copies of itself into other executable code or documents. A computer virus behaves in a way similar to a biological virus, which spreads by inserting itself into living cells. Extending the analogy, the insertion of a virus into the program is termed as an infection, and the infected file (or executable code that is not part of a file) is called a host. Viruses are one of the several types of malicious software or malware.\n\nn order to replicate itself, a virus must be permitted to execute code and write to memory. For this reason, many viruses attach themselves to executable files that may be part of legitimate programs. If a user tries to start an infected program, the virus' code may be executed first. Viruses can be divided into two types, on the basis of their behavior when they get executed. Nonresident viruses immediately search for other hosts that can be infected, infect these targets, and finally transfer control to the application program they infected. Resident viruses do not search for hosts when they are started. Instead, a resident virus loads itself into memory on execution and transfers control to the host program. The virus stays active in the background and infects new hosts when those files are accessed by other programs or the operating system itself.\n\nCheck out this movie on Virus replication :\nhttp://video.google.com/videoplay?docid=9192961636386984286&q=computer+virus\nhttp://video.google.com/videoplay?docid=-7821323279275205551&q=virus\n\nALso check out the movie ANTIVIRUS:\nhttp://video.google.com/videoplay?docid=3481400607478146088\n\nThe best Antivirus to prevent Virus Infection is Norton Antivirus, but it is heavy on system and is generally in 60 day trial version forms. I personally like Avast, because it is light weight and is free.\n\nI have a few Free Antivirus programs I can reccomend:\n\nhttp://www.avast.com/ avast!\nhttp://www.free-av.com/ AntiVir HBEDV\nhttp://free.grisoft.com/doc/ AVG Free Edition\n\nAlso, if your willing to experiment:\nhttp://www.microsoft.com/windows/onecare... Windows OneCare Beta\n\n\nThe best resource for antivirus:\nhttp://www.faqs.org/faqs/computer-virus/alt-faq/part1/\nhttp://www.faqs.org/faqs/computer-virus/alt-faq/part2/\nhttp://www.faqs.org/faqs/computer-virus/alt-faq/part3/\nhttp://www.faqs.org/faqs/computer-virus/alt-faq/part4/