This is a very recent event, and I tried to keep track of what I did so I could recount it here if I needed to.
Last night (night of August 11) I left my Toshiba laptop on to defragment the data overnight and set it to not sleep on its own while plugged to the power cord. When I got up at 9 in the morning my Toshiba had a black screen, was still on and making a weird and dulled 'brrr-rruh' noise over and over again. I couldn't get the computer the respond or get out of the black screen so I shut it down by holding my finger down on the power button.
I turn it back on and to my surprise I find out that it had a windows update overnight and was configuring the updates. However, it stayed on the 'configuring updates stage 3 of 3: 0% complete' screen for a ridiculous amount of time and so I get on our family computer, googled and found out that there is a windows update that causes windows vista to go through an endless loop. So I turned it off again, and restarted it and entered the F8 advanced startup repair and did a system restore to the latest windows update time (which was last night at 11-ish when I was still awake and using the computer), hoping that it would at least get rid of the endless loop. My Toshiba hasn't been in use for a long time (since June 2010) because of startup problems which were just recently remedied so I am just getting these particular updates now.
I got rid of the endless loop, but when my computer started up, it hanged on a black screen where only my mouse cursor shows up after the screen where you see the word 'microsoft corporation' with a loading bar above it. It hangs on the black screen for a while and then I get to the 'please wait' which lasts a lonnnng time before I can login. When I logged in, it also took a long time to load everything and my windows vista slowed to a crawl in everything; internet was slow, getting to control panel was slow, even right clicking a folder froze up the entire computer for a good 30-40 seconds before the menu popped up.
Accessing the family computer again told me that particular windows updates incompatible with vista could cause it to run terribly slowly. So I went about uninstalling all the windows updates that I got on August 12th 2011, and also some other programs I didn't need with the Control Panel. I restarted the computer and Voila! My computer is significantly faster than before.
However, the computer still hangs on a black screen with a mouse cursor everytime I restarted it, after the 'microsoft corporation' loading screen and before the 'starting windows' screen. I have googled for info of how to deal with this but with all the people who have a similar problem cannot log in, while I can. I did find another who had the black screen hanging and was able to log in but it was right after he logged in and not before.
Hopefully someone can tell me what I did wrong or what to do to fix it with my lengthy story, because I know little about computers. It was only yesterday (same day when I was defragmenting my Toshiba) that I found out such a thing as defragmenting even existed even though I've been using computers since 2000.