My Hdd is running flat out even when im not using computer

The manufacturer will have a diagnostic on their web site.

If you do not know the manufacturer right click My Computer then click Manage then Device Manager

Click the + next to Disk drives and you should see the ID.

I would run the diagnostic and see what comes up. Also it is a good time to back up any important data to another drive or disks.

used powemax 4.23 HDD is fine must be a software problem?

Monitor your Task Manager under the Processes tab.
Note the CPU usage as well as any process that is drawing the CPU usage.

Right click an empty area of your Taskbar or press Ctrl Alt Delete to open the Task Manager.

Thanks jephree
the problem is wmpnetwk.exe from windows media update
now i have to find out how to fix this crap
auto update sent it to me been having this prob ever since
cant find it in add remove list seen it in task manager

You can End Task it in the Task Manager then:
You can disable in via start > Administrative Tools > Services > Windows Media Network Sharing Service