how can i prevent some users form using windows media player

I want to set a timeout period of 15 minutes to all computers in our domain.  
I'd prefer not to use a screensaver (as they tend to stop some functions ie:
serial port).
GPO only lists the screensaver method.

my system is joint to network as domain, i have administrator privileges to
my domain account as well. All i want to do to prevent other domain users to
login to my system with their user/password?
Is their anyway that I block other users of network to connect to my PC

I just noticed an odd file folder on my 2nd partition (drive E), and
wonder if it is malicious.  It has the name d0373a4929ad1ee338...  only
1 file there - msxml4-KB927978-enu.log
This .log file is 281 kb, and I've copied the beginning of it below.

I have a Del laptop and I can't get auto complete to work. I have it set up
and everytime I enter a password I get the message asking if I want to save
the password, but it never does. I am running windows xp home edition. I have
spent hours trying to figure this out-Help??