its probably malware or a conflict with other programs you have installed (THAT ARE PROLLY MALWARE)
i also had a similar problem and after I went through the programs list and deleted a bunch of shit i didnt want (especially the old updates of adobe flash) and did some malware scans and shit it practically forced updates down my throat
but i dunno for sure just trying to help. i think you can also download the new service packs manually and install them without using their updater.