[boxcorner]

Calibre has been working smoothly without a hitch, until now ...
Now it gets device information, but fails to get list of books on device.
Have tried reconnecting USB, repeatedly, but it still fails to get list of books.
Have upgraded from 0.7.29 to 0.7.31 but it still fails to get list of books.

Error details:
(30, 'Read-only file system')

Traceback (most recent call last):
File "/home/kovid/build/calibre/src/calibre/gui2/device.py", line 63, in run
File "/home/kovid/build/calibre/src/calibre/gui2/device.py", line 305, in _books
File "/home/kovid/build/calibre/src/calibre/devices/prs505/driver.py", line 139, in books
File "/home/kovid/build/calibre/src/calibre/devices/usbms/driver.py", line 164, in books
File "/home/kovid/build/calibre/src/calibre/devices/prs505/driver.py", line 165, in sync_booklists
File "/home/kovid/build/calibre/src/calibre/devices/prs505/sony_cache.py", line 721, in write
IOError: [Errno 30] Read-only file system: '/media/READER/database/cache/media.xml'

I haven't intentionally changed any files to read-only.
My OS is Linux Ubuntu 10.04 LTS
Any help would be much appreciated.
Thanks in advance.

Addendum
Tried both the binary and source installs again.
Source install generated the following:

~
No package 'poppler' found
~

Used Synaptic Package Manager to install python-poppler and python-poppler-dbg

Re-ran sudo python setup.py install
this time I noticed something else:

~
No package 'MagickWand' found
~

Used Synaptic Package Manager to install libmagickwand-dev

Re-ran sudo python setup.py install
this time I noticed a number of sqlite_custom errors
still groping in the dark ...will try doing a complete uninstall, resinstall and reboot