What viruses may do to a computer.

I think you may experience when you are infected with a virus. Remember that you also may be experiencing any of the below issues and not have a virus.
· Deleted files.
· Various messages in files or on programs.
· Changes volume label.
· Marks clusters as bad in the FAT.
· Randomly overwrites sectors on the hard disk.
· Create more than one partition.
· Attempts to access the hard disk drive, which can result in error messages
· Causes cross-linked files.
· Causes a "sector not found" error.
· Cause the system to run slow.
· Logical partitions created, partitions decrease in size.
· A directory may be displayed as garbage.
· Directory order may be modified so files, such as COM files, will start at the beginning of the directory.
· Cause Hardware problems such as keyboard keys not working, printer issues, modem issues etc.
· Caused keyboard keys to be remapped.
· Alter the system time / date.
· Cause system to hang or freeze randomly.
· Increase file size.
· Increase or decrease memory size.
· Randomly change file or memory size.
· Extended boot times.
· Increase disk access times.
· Cause computer to make strange noises, make music, clicking noises or beeps.
· Display pictures.
· Different types of error messages.