[snackereen]

1st step: get rid of MSN.... seriously. That's probably one of the most used application to spread viruses.

2nd: get some free antivirus-tool (kapersky, antivir), see if it can clear the virus (try several different programs to get rid of it)

3rd: if none of the tools work, your (last) option will be a total reinstall. That hurts but it WILL get rid of any virus you have.

Further advise:
- install a firewall, virusscanner, scriptblocker, ad-/popupblocker, and download all the security updates regularly.
That might prevent you from catching another one in the future (even if there will never be a 100% protection)
- use a under priviledged windows account for playing (and your sister). You don't need to be an admin to surf the net, so create a normal "user" and use it for surfing/playing etc.


Needed information to get rid of it: the name of the virus would help or an explanation of what it does (how did you notice you have one?).

-----> tell your sister not to click on any banner/button or download every fancy stuff she sees on the internet ;)