Update:
For those who are curious, I use Calibre with both Windows 7 (on a GA-965P-DS3 based PC) and OS X 10.6.4 (on an early 2008 white MacBook). The fact I can use it on both platforms is one of the reasons I'm "test driving" Calibre.
The errors reported below occurred when using Win 7. If it matters I could try to duplicate them with the OS X flavor of Calibre.
The database/library is shared via my local LAN by storing it on a PogoPlug/Dockstar device. FWIW, I get the same errors if I copy the library to a local hard drive on the PC. I'm not sure what sort of corruption the database has, but it is annoying to not be able to "fix" it. 
I've been trying out Calibre trying decide whether I love, like, or hate it. At the moment, I'm learning towards I like it when it works.
I recently installed v0.7.16. I have also recently started getting errors that something is wrong with (at least) one of my Calibre databases. I have no idea is there is any connection.
Below are the error messages I am receiving when (1) trying to check the database integrity and (2) when trying to close the Preferences dialog window, respectively.
I have no idea what to do next other than to delete and re-add everything. I do
not want to do that and hope there is another way to recover from this.
Code:
ERROR: Error: Failed to check database integrity
Traceback (most recent call last):
File "site-packages\calibre\gui2\dialogs\config\__init__.py", line 964, in run
File "site-packages\calibre\library\database2.py", line 2055, in check_integrity
File "site-packages\calibre\library\database2.py", line 769, in clean
File "site-packages\calibre\library\database2.py", line 756, in doit
File "site-packages\calibre\library\sqlite.py", line 202, in run
DatabaseException: Connection closed Remote
Code:
ERROR: ERROR: Unhandled exception: DatabaseException:Connection closed Remote
Traceback (most recent call last):
File "site-packages\calibre\gui2\dialogs\config\__init__.py", line 903, in accept
File "site-packages\calibre\gui2\dialogs\config\__init__.py", line 789, in apply_custom_column_changes
File "site-packages\calibre\gui2\library\views.py", line 227, in save_state
File "site-packages\calibre\gui2\library\views.py", line 221, in write_state
File "site-packages\calibre\library\prefs.py", line 51, in set
File "site-packages\calibre\library\prefs.py", line 44, in __setitem__
File "site-packages\calibre\library\sqlite.py", line 202, in run
DatabaseException: Connection closed Remote
Ooops! Forgot to include the error message I get when I exit/close Calibre.
Code:
ERROR: ERROR: Unhandled exception: DatabaseException:Connection closed Remote
Traceback (most recent call last):
File "site-packages\calibre\gui2\ui.py", line 569, in closeEvent
File "site-packages\calibre\gui2\ui.py", line 461, in write_settings
File "site-packages\calibre\gui2\init.py", line 258, in save_layout_state
File "site-packages\calibre\gui2\library\views.py", line 227, in save_state
File "site-packages\calibre\gui2\library\views.py", line 221, in write_state
File "site-packages\calibre\library\prefs.py", line 51, in set
File "site-packages\calibre\library\prefs.py", line 44, in __setitem__
File "site-packages\calibre\library\sqlite.py", line 202, in run
DatabaseException: Connection closed Remote