I did set up my external disk as time machine by mistake and now I just want my goflex to be a simple backup drive, how can I reset it as origine?

SOURCE: Trying to install FreeAgent GO 500G as backup for Server 2003

Installation isn't possible directly from the Harddisk.
Try download from http://www.seagate.com/staticfiles/support/software/FreeAgentCN.zip 
Good Luck.

Uwe

SOURCE: How do I work on my data on the Seagate FreeAgent

Assuming you are using a Windows operating system, you can just plug it into your computer's USB ports, and the computer will recognise it as another hard drive.

Instructions:
Double-click on 'My Computer' and take note of what drive letters are there (C:, D:, etc.) before you plug in the Seagate Freeagent.
Plug in the Seagate Freeagent. You'll see the new drive, likely E: or F: (depending on what is already there before you plugged in the Seagate Freeagent)
Double-click on the new drive, and it'll open up and you'll see the files stored on that drive. You can drag and drop files and save to this drive like any other folder on your computer.

SOURCE: The Samsung Freeagent GoFlex external

This is a good read on what this error actually means:
http://www.softwarepatch.com/tips/cyclic-redundancy.html

What I recommend is reformatting the drive under Computer Management, and seeing if that fixes the problem.

SOURCE: can you use a Seagate 500GB FreeAgent GoFlex

Yes, but because it's a hard disk and has low transfer speeds it will actually slow down the pc instead of making it work faster. Ready boost is designed to be used only with memory sticks of the latest generation.

SOURCE: I have a seagate goflex

I have the exact same drive. If off-the-shelf cables are not working (which is odd) I would suggest buying a USB 3.0 extender. This will extend it about 3 feet. You can purchase them for <$5 online! Let me know if this helped out any.