well. In fact. It can. But first you have to see what kind of program it is:
-Virus: created primarilly by the same that create the anti-virus, to make us buy it. They are just little fuckers with no other intention that to break the computer. But can be easilly countered. The problem with this little dudes is that they are spammers, which means that once one is installed it will try to connect to internet passivelly to bring a whole lot of friends that infect everything. They are like ants: one is just a stupid thing you can stomp. A lot means you really are fucked. And they come in packs!
-Malware: now here comes bigby! This are not like ants, this are angry famelic bears. This fuckers are actually created by crackers to shut full computers down quickly, and then end up released somehow (sometimes it's the cracker itself, sometimes a malfunction, sometimes the victim expectinng it to come back to the cracker) This ones are easilly to spot, and that's it's major weakness, because of that they are proggramed to make ridiculously high amounts of damage to your software before you can do shit. But once you get the computer to a technician he can easilly take them down by oppening the computer with "system symbol" (ascii code) or connecting it to a second computer, but normally you'll have to reset your harddrive. (Dunno if that was the correct translation) They're effects are various (like making your computer shut down at random time intervals, making the notebook be black with white letters, breaking all icons only showing the "broke image" icon...) some of them are weird (like one that made a giantic screen appear saying it's the police that has seen you looking for porn and blocked the computer as a punishment (obviously a lie)) and some of them are even funny (like one that made a multi-colored ball appear moving at random directions on screen, or another than said "hardwire centrifugating" and suddently made the screen turn at high speed) but they are all exhasperating.
-Spyware: AHH THE EVILNESS!!! This ones are the ones I hate the most. They aren't just wrecking balls. They are activelly trying to STEAL your data. They come in various kinds: Memory readers, auto-typers and worse. The memory readers scan your data and send it through internet to a webpage where it's passed through a program that searchs common words to detect all the paswords and monetary things you have. Then they use it to clean yout bank account. The auto-typers are easier to spot: Babylon, searchQ, ASK (ASK is the most dangerous and common of them) They appear as if they were suddently your main browser, or a tool bar on top of your internet window. But what they do is Scan all what you type when you have your internet application open, and then they send it to a webpage just like the memory readers, again they are activelly trying to steal as much money from you as they can. Beware of them.
Also. An added problem with them is that the anti-virus anti-malware or anti-spyware normally deletes all the infected parts (there is no other way) so it breaks a lot of programs doing it's job (it's like quimiotherapy, it kills the infected cells, and the non-infected suffer too) so it's like a secon infection untill you set everything on again.