Man! You guys/gals are just teasing me!
OK, it's not like I have problems with every update; just maybe three (or so?) that have really gotten me.
First one was back in April 2006, maybe? The update that installed a program that somehow facilitates the prefetch function. That same update also added, I believe, the new and - IMO, not improved - WinSxS manifest mess, which in turn messed big time with XP's DEP, or Data Execution Prevention. That update and the idiocy of a few developers caused me a lot of grief. TechSmith was one, and Mindjet was another. Both got lazy and when Windows Installer 3 was released instead of building new installer packages in WI3 they simply copied over the code they had used in Windows Installer 2 to the new WI3. Version 2 hadn't had to deal with the new WinSxS manifest stuff, but 3 did. That made both SnagIt and Mind Manager Pro go haywire after I installed them.
Both now must be listed in my DEP exclusion list or they will not even appear when I try to start them. (Or at least until I reinstalled Windows after that!)
Now this post will draw out another dozen members here who will post how they are soooo lucky! (Creeps!)