all command very slow

allo,
i have computer after 6 houre work on screensaver
when i clic on start or any command they wait 30sec to do and if i put 2,3 command same time i wait 5 minute to see the command
ex:start,programme,accessoire,system tool,defrag
this command i need to wait 30second after each command.when i open computer is fast.thank you