Most reputable Internet sites and online services now scan all of their files for viruses but that still does not guarantee that all their files will be virus free. You can also catch computer viruses from e-mail attachments. Always save and scan any e-mail attachment for viruses before opening the attachment. Even brand new shrink-wrapped software has been infected with viruses. Your computer hard drive is constantly running out of free space even though you have not installed any new software.
Programs take longer and longer to load.
Hard drive runs even when you are not accessing it. Files appear on your computer with strange names you don t recognize. Strange graphics appear on your computer monitor. Your conventional memory is less than it used to be. Programs act strange or erratically.