Could be, never know, could be a Trojan and somebody playing games. But very well may be another issue. I would try this first,
Ad-Aware SE Personal
I run this daily
I update once a week (keeps bad pages with known malware that cold cause damage from being displayed.)
Spybot - Search & Destroy
Daily or every other day
This is one I only use once a week or month lol but good to have
In order to get full use of this one you have to buy it but has a free trial. Good program to have and run before you run Hijackthis. (just another tool to remove spyware that the other two may miss) Only download if you are having a serious issue unless you want to pay and have it.
Download and update (update is very important before you scan) boot into safe mode (You do not need to boot into safe mode every time to run programs. Some malware cannot be fully removed or detected unless you are in Safemode, This is why I recommend running it the first time in safe mode then perhaps once a month in safe mode)
With some computers if you press and hold a key as the computer is booting you will get a stuck key message. If this occurs, instead of pressing and holding the "F8 key", tap the "F8 key" continuously until you get the startup menu.
Scan the computer,
Boot backup into Normal mode, download
CodeStuff Starter manage your startup programs
Disable all startup programs that you "do not" need running at startup.
A guide to hep keep a smooth system.
Maintain your system with Windows XP
The best program to use for defragging