Cannot copy thumbs

Hi
i have win2000 domain at work and i am the network
administrator of it , some day when i try to copy some
files from server to another one it appear me message
says >>>>>>>>>>>>>cannot copy thumbs: access is denied .
the source file may be in use <<<<<<<

but i am sure its not in use so what is the possible
reasons for that case , after i do some tries i descover
is some folders is corrupted but the contents is ok but i
cant do that manually , so if some body have any kind of
help for me i'll appreciate verry much

thanks

Maged