re this thread http://social.technet.microsoft.com/Forums/en/w7itprogeneral/thread/53779044-d453-458b-b8c4-96d41711ea69 which is locked as answered. It's not. I am trying to backup a data folder of about 56GB to a USB drive. I get the error "the filename you specified is not valid or too long. and one of the files I'm trying to backup is C:\Data\DOG_TM_Manual.pdf not too long as far as I can see. It is not invalid, I can see it, and it's all there. I can move the file to another folder (can't copy it from there either) or rename it but not copy it. If I click "skip" it then stops on another ordinary file. If I select "do this for all current items" then 1000's of files don't get backed up. Did a filesystem check incl surface scan (ugg) with no problems. All the files rejected are ordinary files (txt, pdf, jpeg's etc) and can be used, viewed, edited, renamed, deleted and moved. I can move Data to somewhere else (ie C:\Temp) with no ill effect to the files but still can't back it up. So this problem is not a path or filename too long problem and the files are not invalid!! Maybe MS should get Windows 7 right before moving on the Windows 8.

Hi, How about renaming the pdf file to a simply one? (Don't contain "_") Meanwhile, use system file checker for a test. http://support.microsoft.com/kb/929833Niki Han TechNet Community Support

Hi, How about renaming the pdf file to a simply one? (Don't contain "_") Meanwhile, use system file checker for a test. http://support.microsoft.com/kb/929833Niki Han TechNet Community Support

what about the path to the usb where you are copying it too?