computer help

[LTZ400rider]

my dumbass sister came home from college and once again ***ed my computer up, now i have a password so she cant use it. well she used internet explorer, which i never use cuz it allows spyware. i always use mozilla. anyway i deleted as much IE stuff i can find on my computer, and i use 2 spy things, ad aware and spybot search and destroy. well i been gettin alot of junk lately like pop ups and slow loading. well now today my comp is infested with ads and all that stuff, when i clean it all up with the 2 programs, ill do it again 1 minute later and it will be loaded with like 20 more programs. i never go on internet explorer either. i went to remove programs and didnt see anything that wasnt suppose to be there. any solution on getting rid of this stuff completely before it spreads, or do i have to completely delete my computer for the 4th time

[300ex13]

i kno ur problem...someone used IE to find a 'backdoor' to your puter...when ur on the net and ur puter sends info to the net and the net sends it to u it uses only a few ports...ok well while ur sis was on someone found an open port that u didnt kno was open and cracked into the puter...still with me? neways theyre just gonna keep sendin you stuff and are waitin to send u a trojan or virsus and controil you whole puter (which is not good at all) something similar to u happened to me and lost my whole puter from bout 5th grade til this year (sophomore in highskool)...if i lost u anywhere in this im me, e-mail me,or pm whatever an i will try to explain it better