Does her mouse seem to go a bit odd just when she opens her myspace page or does it do it even if the her internet browser is closed? Does it do it on other internet sites (IE: cnn.com, google.com etc etc)... If just on myspace does it happen when she is setting at the home page NOT logged into her account? Have you cleared your internet cache (running IE7 click tools -> delete browser history -> delete ALL). It could be remote desktop but she would have had to allow it.......................... Its possible.... well there are a lot of possibilities here.
If she is still in your house you should kick her out for using myspace...
But if thats not possible and her computer has been compromised and resides on the same network as yours then yes you should be some what worried. Maybe more for her sake then yours but still a bit for your own system. Reason being is if someone has access\controll of her system (most likely a rootkit of some sort) one of the first things they will do is scan the rest of the network segment she is on to see who is out there. Your machine will respond to this query in a manner to inform them the type of operating system (most likely XP) that you are running.
They will then proceed to look for possible vulnerabilities that your machine might have that would allow them access. Even if they dont find anything (Most likely will) they could always just install a sniffer on her machine and monitor the traffice, on a scheduled basis send this traffic back to them selfs (most likely another zombie system) and run it through a analyzer looking for specific things like bank, credit card, login, logon, password.. etc etc etc.. so yes you should be a bit worried...
Now that the complete scare tactic has been put out there you need to look at it from another perspective.. What do you have that is so important that someone would spend their time trying to get. PCI requirements require banks to have SSL connection (encryption) to their sites so unless they get a keylogger on your machine they are not going to get that info (Well they could but we are getting pretty elite at this point). Again most places that allow online banking will be some form of secure connection as well. Most peoples machines get hijacked anymore so people can increase there bot network (Russian buisness network, ya baby) a bit higher, script kiddies are trying to improve their skills or test a new tool. Honestly run windows firewall, run a basic FREE firewall like AVG, run something like Spy bot search and destroy once a week or month, apply software updates (not just microsoft, others as well like adobe & quick time might ring a bell here) and just try to make good judgement calls on your internet browsing.
Without seeing the machine (your daughters) or knowing more info I cannot really give you detailed info on what really the issue is or what best to do to resolve it. Most people are going to recommend downloading "super tool" but the problem is that if its a root kit thats worth anything it can easly mask itself from a scanner. Considering the way you posted your question you dont appear to have the skill set to run some of the more advanced tools to look for the groove stuff (again nothing against you). See if there is anyone on this forum in your area that has some skills that might be willing to help you out.
