might be that kind of program i mention before that cause your cursor to move at certain time.
Some handy tips against spyware:1.Never use administrator account for anything unless you gonna install some software that you trust or make some changes to the computer.
2.check for spyware regularly
3.try not to go to adult sites ,warez sites etc (im not saying every warez and adult site does this but some do ) cause they install dialers (dialers are those nasty things that dials your com to a porn number and get a huge amount on your bill)on your com somehow on some occasion it can still do it if your not running admin.
4.try not to download free software like kazza, imesh etc as they are ridden with spyware (im not saying dont download any free software just download the ones you think doesnt contain nasty stuff)
5.update your spyware detection program regularly
6.add yours (i think there is more thats all i can think of so far)
someone mention there mouse moves when they go to a site
some site has script such as javascript that can do stuff to your cursor(i dont know much about javascipt cause i never used it)