I have the same problem. Removing SupportAssist was a challenge on it's own. Please help DELL! I've been wasting a lot of time on this issue and reading the numerous threads , it seems I'm not alone! thank you in advance Hi everyone, just wanted to let you know, I did a clean install of Windows and Dell Update and Dell SupportAssist is working great again. 
I tried to install SupportAssist but it shows me that installation is cancelled because SupportAssist  is only for Dell and Alienware PC's.. I have Dell laptop.. How can i fix it or what should i do?
SupportAssist installer