Back button skipping over pages, etc

I am not sure what forum to post this question in, but I guess I will post it here.

For the past couple of days, my computer has been driving me nuts when using my mouse. For instance, when I am clicking through a website going through many pages and then clicking the back button, it will completely skip over some of the pages. If I click page 1, then 2, then 3, and then click the back button, it will go back to page 1 (completely skipping over page 2). But if I click the forward button, it goes to page 2.

Also, when deleting mail in OutLook Exp., it will delete 2 emails in a split second, when I am only wanting to delete one.

Another problem is trying to copy and paste. If I try to copy a sentence, and hold down my mouse button, by the time I get to the place where I need to stop and hit paste, the blue highlight goes away. And sometimes it will only highlight one word when I am trying to highlight a whole sentence.

Is there a setting I need to fix, or is it possible there is something wrong with my mouse (maybe the left click button??)

thanks for any help!