Automatically last desktop icon is selected

Hello,

Give me a solution for this......

When I start my computer last icon of the desktop is automatically selected.
When i click on other icons only the last icon is opened.
I can open the icons if i press the TAB button and refresh.
But it is limited to some time only.
Also webpages are scrolled down automatically till the end.It stops if I press TAB. But after some time it stars again.