please help when i put pc on it says keyhook exe couldnt be found ive tried the link to reinstall somthing but cant do it my pc has been going really slow i havnt a clue how to fix it help me]

Judging by the name of the file it would seem that you have a virus.

Viruses ussually hide them selves inside your computer and slow down your computers performance, a possible way to fix this would be to get an antivirus. And if then the problems not removed or fixed you will have to reformat your computer, or get it repaired

some good antiviruses i think are:
McaFee - my personal choice
AVG- which is free
NOD32
Avast

for your situation in particular i suggest trying AVG which you can get from here and also i suggest you get antispyware protection, a reasonable one would be Spybot, which you can get from here if problems still persist go to your local IT technician. Hope this helps

Or it's just simply a safe app with a wierd name:
http://www.neuber.com/taskmanager/process/keyhook.exe.html
http://www.processlibrary.com/directory/files/keyhook
http://searchtasks.answersthatwork.com/tasklist.php?File=Keyhook (marked as "not OK" because of known issues here)
http://www.what-is-exe.com/filenames/keyhook-exe.html

if this isn't enough to explain what it is, just google keyhook.exe