Adding books Error

When I try to move a book into calibre I get the following error:

Traceback (most recent call last):
File "site-packages\calibre\gui2\add.py", line 127, in start
File "site-packages\calibre\gui2\add.py", line 221, in add
File "site-packages\calibre\gui2\add.py", line 234, in add_formats
File "site-packages\calibre\library\database2.py", line 1348, in add_format
File "shutil.py", line 48, in copyfileobj
IOError: [Errno 22] Invalid argument

Any ideas?