I would check a couple of places to see if you can narrow down where the program is running and what it is. First you can check your Task Scheduler to see if something got setup to run at 11:00. The easiest way to find Task Scheduler is to just do a search for it from the Start menu. If there is a task there you should be able to find out information such as what the program is and where it is running from.
Cross site scripting is a type of vulnerability that can be found in web applications which can enable attackers to inject client side scripts into web pages. This vulnerability can be used by attackers to bypass access controls such as the same origin policy. Cross-site scripting is a very common practice. Its impact may range from a annoyance to a serious security risk. Depending on what program is informing you about this cross scripting will determine if its something to worry about or not.
You can also use the System Configuration Utility (MSconfig) to see if something is set to load when you boot your computer. You can disable any suspicious programs from here.
I would also run some spyware scans to make sure you don't have any infections on your computer. There are plenty of free and effective programs that you can download and install to do thorough scans. Its best to use more than one program to make sure nothing gets missed.