I am not quite sure when I started noticing it, but I realized that Windows had updates to install every single time I wanted to shut down my laptop. I went and checked my update history, and there was a long list of failed updates, all of them security updates for .NET Framework 4. I tried repairing my .NET installation with the standalone installer, and it failed (The logs are here: http://dl.dropbox.com/u/26799582/Microsoft%20.NET%20Framework%204%20Setup_20111221_223635735.zip, the text file is the one linked to in the html file.) I also had a failure when trying to install Visual Studio 2010 Service Pack 1 through Windows Update, allthough I do not have the logs from that.
EDIT: I forgot to mention that I am running Windows 7 Home Premium (x64)