When you make Windows updates, the files and folder will appear.
If you are not making updates and the files still appear, Some website has
hijacked your homepage.
1. Use the following scanners to find and remove the website.
SpyBot S&D searches your harddisk for so-called spy- or adbots;
http://security.kolla.de/
or
Adaware
http://www.lavasoftusa.com/software/adaware/
or
CWShredder
http://www.spychecker.com/program/cwshredder.html
2. Some porn websites redirects links to their websites using your HOSTS
file. Do a search for the HOSTS (without extension) file and remove the
entry.
3. If still no joy, download HijackThis from Spywareinfo download page
http://www.spywareinfo.com/downloads.php
Run the program and you will find many entries. Most are OK. Post the log. I
will find the problem for you.
4. For future preventive maintenance, make sure programs cannot just
download on your computer without your permission. From the Internet
Toolbar, go to Tools > Internet Options > Advanced. Make sure "Enable
Install On Demand (Internet Explorer)" and "Enable Install On Demand
(Other)" are unchecked.