Well netbooks can be somewhat lacking on resources, so if you have MBAM pro resident, it and avast are going to be loading fairly early in the boot.
For me .net framework has been an unmitigated disaster with by far the worst windows updates ever, they are an absolute nightmare. I have one program that requires .net framework or I wouldn't have it on my system at all.
I too have had issues with .net updates and it was very painful when I was on dial-up, getting a friend to download the packages for off-line update. I got all the way up to .net 4 installed and even then WU said I needed a .net update at about 60MB, I gave up and uninstalled every bit other than the old version 1.0 required for that single program.
Now I don't know if .net was your problem, but you certainly have to manage what is run on a netbook if it is low on resources. It could however just have been a computer hiccup.