How to defragment your computer

follow these steps:

1. Make sure the computer and external hard drive are powered on.
2. Safely remove the drive from the computer (if possible).
3. Disconnect the external drive's USB or FireWire cable.
4. Disconnect the power supply plug from the external drive.
5. Power off the computer.
6. Disconnect the computer's power supply cord for 60 seconds.
7. Reconnect the computer.
8. Power on the computer.
9. Connect the power supply to the external drive.
10. Connect the drive's USB or FireWire cable and check for detection.

If that does not correct the behavior, and if the drive is also not detected by your computer, the blinking light is probably a symptom of a larger problem. If those steps do not return the drive to correct function, it is very possible, even probable, that the drive has failed and needs to be replaced

Print speed can be affected by three important factors:
Available computer RAM
Available computer hard drive space
The HP All-in-One product paper sensor
Follow the steps below the ensure the computer is operating properly.

Step one: Verifying the amount of RAM
Verify the amount of RAM installed in the computer.
Determine the amount of memory currently in use by background programs or processes.
Programs/processes will run in the background even when no applications are running. Most of these programs/processes will be indicated by an icon in the lower right corner next to the time.
Less memory available for applications will result is slower processing time and consequently, printing speed.
To determine processes running in Windows 2000/XP , do the following:
Press Ctrl , Alt , and Delete simultaneously and then release.
From the Windows Security box, select Task Manager.
Click the Processes tab to view all running processes.
Click the Performance tab to view the total and available amount of memory.
To determine processes running in Windows 98 , do the following:
Open the Device Manager .
Click the Performance tab.
The available system resources will display as a percentage.
Turn off unnecessary background processes.
This will free up system resources and increase printing speed.
To turn off processes in Windows 98/ME/XP , do the following:
Click Start , Run , and type msconfig.
From the System Configuration Utility, click the Startup tab.
Determine what processes are unnecessary and remove the checkmark those items.

Step two: Verifying the amount of hard drive space
Follow the steps below to determine the amount of hard drive space on the main drive.
Open My Computer , right-click the C drive, and then click Properties .
This will display a chart along with the total hard drive space, used space, and available space.
Verify that there is at least 2-3 GB of hard drive space available.
The computer will require at least this amount to process printing data for simple text files, more for image files. The lower the amount of available hard drive space, will greater the time to process print data.
Step three: Ensuring the paper sensor is clean and not damaged
The all-in-one product paper sensor plays an important role in determining the print speed.
Printing a self-test or demo page will ensure that the paper sensor is in proper working condition. If the page completes in less than 40 seconds, the sensor is working correctly.
Even if the sensor is working correctly, the printer driver might need to have the paper sensor turned off. To turn off the sensor, follow the steps below:
Open the Printer folder, right-click the printer and click Printing Preferences or Properties.
From the Properties box, click thePaper/Quality or Features tab.
Under the Paper Type section, open the menu and select Plain Paper instead of Automatic.
This will disable the paper sensor and increase the print speed

I devised these simple steps that tend to remedy quite a few issues with most portable / external hard drives (though not always)
A few things to check but assumes USB and Windows for other interfaces / operating systems similar steps may be adapted to suit.

1. Ensure it is connected directly to the computer to a USB 2.0 port not a USB 1.0 port as this can have effects on performance and reliability
2. Use only the cables that came with it NOT one that fits that may have been lying around or is longer. Not all USB cables are equal even though they should be)
3. Do not connect through an external USB HUB unless that hub is USB 2.0 AND has its own power supply.
4. Use ONLY the power supply that came with it if it has an external power supply
Don’t use any other unless you know it has both the same voltage and current rating e.g. 12V 500mA anything rated below that would not work properly.
5. Always use the same port for connecting your devices. Some devices do not like being switched about. If switched they may want to install software / drivers again.
If you checked and fixed anything there and still have issues carry on reading.
Go to your control panel and then administrative tools, select Computer Management.
Now select Disk Management and expand the window.
Your drive should be listed here, if not then you need to check your computer hardware has not got any issues before proceeding.
If your drive is listed and says healthy then right click on it an select Properties, click Tools and then Error Checking, Check now, tick the two boxes and then Start.
This will attempt to fix most minor / common errors on the drive. It may also ask you to restart which is fine. Allow it to finish its work or you could corrupt the drive. If all went well you should be able to use it normally again.
If you drive was listed but did NOT say healthy then right click and select Format. Choose NTFS as the file system and do not tick any boxes you do NOT want quick format. Again start and let it do its thing. When it is done restart your computer and you should be good to go.
If you still have problems with the drive you might want to look at other areas.