So here are some guides to help you fix it.

If you’re like the majority of computer users you probably only use the thing for surfing online, checking email, or stalking an ex on Facebook.  While you claim that you haven’t downloaded anything malicious, there are probably a bunch of programs running in the background that you didn’t even know were there. 

A good way to check these out is to check your task manager. To view this hit CTRL+ALT+DELETE (if you have a Mac, kill yourself) then click on "task manager" if it doesn’t come right up. 

Now you’re going to see a bunch of things that are probably moving all round the window. To see what is taking up the majority of your computers memory click the tab “processes” and under that tab there should be another one labeled "memory." Click on that and it should arrange the list in descending order, if not, click it again.

The larger the number, the more “energy” it is taking your computer to run. All of these add up, and if you see a bunch of them, it would probably be a good time to delete some of them. You can do this in your computers “add/remove” programs located in your control panel.

Another thing that may affect your start up time is that you have a bunch of things starting automatically. You want to try and make only the necessary programs run at start up.

To monitor this, you want to get to “msconfig.”

If you have Windows Vista or 7, just click start and type that in. if you have an older version, click START>RUN> then type in “msconfig" then hit RUN.

Now that you’re at this window called “System Configuration” click the tab labeled “Startup.” This is everything that is starting when you log on to your computer. There are probably a bunch of them there but the more you can un-check the quicker your computer will start up.

Now its going to ask you to restart and when you restart the programs that you un-checked are not goign to start up! There might be another window that appears when you boot your computer after the restart just verifying the changes that you just made.

Also, check out the page under "Virus" on this site and run some of those programs that are at the bottom. (Link)

Or you can take it to ME and I can clean it up for you!