Hi Xemem.

Not sure about the other things you added in your post. Is the system working well other than this Flash problem? If so I will the rest there and concentrate on the Flash install problem. If not, perhaps make another thread and detail the other problems?

I would use Adobe's dedicated Flash Player Uninstaller from;
http://kb2.adobe.com/cps/141/tn_14157.html

Download that uninstaller file to your Desktop, then run it. it should uninstall all Flash products from the system.

Then I would reboot, (restart), Windows, just to ensure the registry and any system files have been updated.

Next step, back to Adobe to install Flash, from here;
http://get.adobe.com/flashplayer/

Beware! Look at that web page carefully because Adobe has included an option, (top right of the page), for downloading and installing a McAfee security installer. You may see a different option in your browser. If you don't want that additional utility, remove the tick.

Then download the Flash installer to your Desktop and run it.

See if that works.

Mark