TOHIGHSCHOOLGUY: good news and bad news.
good news is, i know why your computer is misbehaving. you are infected with mutlpile trojans, bots, and spyware/adware/.
bad news, You wont be able to fix it. i cops you, because someone who does know what they are doing can. depending on what your financial status is, i suggest the following. wither bring it into a mom and pop shop, and get ripped off, but if you can afford it, who cares, at least your machine is fixed. or get a thumb drive, and put all the documents, pictures movies, etc on to it that you need. then format the computer. this can be done by either using the cd’s that came with the pc, or if it has a recovery partition, then there will be a utility during initialization (boot up) that will load the recovery tool. hit that, usually one of the function buttons at top of keyboard, and format the pc back to setting at purchase. walla, all clean!
(personally, unless you have programs installed that there is no way you will be able to reinstall later, you should wipe it, because it is really very hard to truly clean a machine.)