Browser is Very Slow and shows strange behaviour.

Hi All,

I am having att comcast broadband internet connection at home(Gateway
computer with Windows XP OS.).

I have been noticing of late that my browser is really slow. As an example,
when I go to any site, it fetches
the page quickly but at the last minute of fetching the page, it seems to be
doing something. That is what I understand
by the status bar that I see underneath. Also in general , I am feeling my
computer is slow.

Also in yahoo mail, after I compose an email, when I press the send button,
nothing happens. That is ,the mail is not
sent and the nothing happens.

Another thing is that, some times I feel my mouse is not responding properly
..

Did anybody notice the following things? Can you please tell me what is the
reason for these observation or is it
a virus. Any suggestions are highly appreciated.

Thanks,