Fan Problems

I own a Dell Dimension 2400 Computer and when i go to the start menu

 to put into standby it stalls out so i have to go under the task manager and click standby.

 Well it says Preparing to Standby, and it makes that sound that goes

 " Tick Dooooo " ( the doooo is like it is powering down) but the front light and the 2 fans

 are still on. When i press and hold the power button for 5 seconds it turns off and no noise

 though. Also the monitor i use ( my TV) is off and like you said you can open and close the 

disk drives. Also i thought it was cooling down from a tiring day of faxing and txt doc and emails

, So i left it running and when i woke up it was still on :( . I clicked the mouse, pressed the 

keyboard and nothing else but the fan and lights

I refuse to pay $900 to $1500 For a new computer