Erratic behavior, windows shifting over, ect.

I've been having computer problems for a while now (five months). my symptoms are: windows shifting over to the right of the screen when you select them, random file opening or option selecting, beeping when booting up, unable to select options, and other things like cursor erratically moving and scrolling windows horizontally to the right, and arrow keys randomly not working. I've reformatted my computer three times, and it works for a little while, then it starts to malfunction, I've tried using my virus scanner and it says that there isn't anything on there, and I've tried using other scanners too. Now whenever I open my comp I have to do a virus scan and the malfunctions stop . But then when I boot up my computer after I finish using it they begin again the next time. Is this fixable? I've tried getting help before on here but I didn't get any replies, I would really appreciate some feedback, or comment of what you think is ailing my computer. I've tried lots of other things, like changing internet browsers, deleting junk files, get tech support over the phone, and updating as much software as possible . Any help would be GREATLY  appreciated. Thank you.

I forgot, my system is an inspiron 1525 laptop, I got it new last september, it's running on vista. Any other things I left out don't hesitate to ask!