Windows 7 does not act properly

I have a PC with a Gigabyte mother board and an i3 processor with 8gig ram and 2 tb hard drive. When I got the computer, it was running Windows 7 Ultimate 32 bit. Once I checked the computer, and found it was 64 bit compatible, I installed the 64 bit version. I did this as a new install. I have had nothing but problems since. I have an intelli mouse which clicks away when I try to go back or forward on a web page. If I try to check a box, it checks and then automaticaly unchecks. I have to keep clicking on it until the check stays. Some web pages won't even work, ie Bank of America Website. I can go to anything I want to except My Portfolio. It causes IE9 to shut down. When I try to open programs, it opens multiple times. I have formatted and re-installed again, but still have the same problems.