PC: Maybe it's because microsoft slipped some greenbacks in all the major antivirus companies' back pockets to make sure they don't record Windows Me as a virus
You are one of the very few lucky ones, mark, because the OS has incompatibilities with some hardware and some software (like that which requires real-mode DOS to run)
There are a lot of features turned on by default that make the OS unstable, resource hogging, and more of an overhead on CPU resources. Like Postcode said, it updates when it wants to without warning, and that can introduce certain security risks.
I found the fact that it tried to hide my own drive from me appalling, and no matter how hard I tried turning Web view off, it would just keep coming and coming.
It's like MS telling you where you can and you can't go, what you can and you can't do, etc etc. Call me nuts, but I also had this really uneasy feeling in my stomach the whole time I used ME.