USB hard drive checking

Hello every body,

I need help on the above subject:
I am currently using XP SP2. I have an external USB HARD DRIVE and have tried without success to have it checked for files and disk defects, bad sectors etc…
When I open Windows explorer, Property, tools and have the drive checked it says that it can only check at the next time the computer is rebooted.
But when the computer is rebooted the drive is not recognized before windows is opened.
So it looks like Catch 22 here.
Anyone have an idea about the problem?
Thanks for your input.