Speedy Netbook Stuck Trying To Install Updates?

My toshiba netbook (running windows 7 ultimate) has been stuck in an updates loop for the better part of the year. Whenever it has wanted to restart for updates, I always let it, but now it gets stuck configuring and sometimes realizes that it's failed and reverts the changes, or sometimes (when it's stuck on the same percentage for hours or even days) I have to pull the battery and restart in safe mode to get it to work again. Now it's really stupidly slow and can't even open firefox half the time. I've taken some basic precautions, like thorough malware scans, backing up all my files on my external hard drive and deleting useless programs, but it's still sluggish and unreliable