A file i didnt download keeps getting onto my Vista! every time i delete it it just comes back on! how do i get rid of it?

I have no idea how this file got onto my computer its an internet file and opens with Mozilla Firefox anyways, I keep deleting this file but every time my computer comes back on its still there.Know my computer is shutting down every time i try and download a file from the internet or if i try to run a program. I am a graphic designer so i really need my computer ASAP! i have no anti virus software running right know so i have a few questions:

  1. how did it get on there?
  2. how do i get rid of it for good?
    3.How do i prevent this from happening in the future?

Answer to 1: i have no anti virus software running

Answer to 2: Download Malwarebytes AntiMalware and an antivirus program, like Avast home or Avg free.

Answer to 3: Same as 2


Antisomething software is not enough to protect a computer from installing unwanted stuff.

Most important for prevention is:
Never use an administrative account for normal work
Make sure you have applied latest patches and security updates for operating system and applications.

And if you allowed to install malware, then the only way to reclaim your computer is to flatten and rebuild.


Disable the internet (unplug it), use another PC to download the new software.

To clean the spyware/whatever: (all free, google them)
spybot search and destroy
Lavasoft Ad-aware
and the above mentioned Malwarebytes

After removing all junk, you need a proper firewall and antivirius (all free):
Avast antivirus, its free just register it.
Comodo firewall (install just the basic firewall, make sure select that when installing). Its free, no registration or email required to use it.

After doing all that, you can enable your internet again.