Hello,
I was renaming books. I have renamed about 100 of them and then an error popped up:
calibre, version 0.8.5
ERROR: Unhandled exception: <b>MemoryError</b>

ut of memory
Traceback (most recent call last):
File "site-packages\calibre\gui2\library\models.py", line 901, in setData
File "site-packages\calibre\library\database2.py", line 1784, in set
File "site-packages\calibre\library\database2.py", line 2083, in set_title
File "site-packages\calibre\library\database2.py", line 611, in set_path
File "shutil.py", line 51, in copyfileobj
File "tempfile.py", line 595, in write
MemoryError: out of memory