Thanks for your replies, people! Computer Hope forum has always been my first stop for solutions to stuff like this.
I went into my control panel and changed the setting so updates would load only on one day per week, instead of everyday. There was also an update waiting to download so I started it off. It hung there for quite a while then finally got to 24%, then it failed and I got an error : "WindowsUpdate_80070017" "WindowsUpdate_dt000"
I suspect it may be this particular update constantly wanting to download and constantly failing and trying again that is causing this issue. What can I do to resolve this?