[Sunnyful]

I've been using Calibre for a while now to manage ebooks with my old Kindle Keyboard. Today I was trying to convert and transfer an epub to my Kindle, and it kept showing the status: Waiting, progress Unavailable, nothing would happen even after quite a while.

I tried closing and restarting Calibre, rebooting the computer, and even deleted and reinstalled the latest version of Calibre, nothing worked. Now, however, when I try to open an ebook from my library or my device in the Calibre reader, I get an error message as follows and it won't open at all:

calibre, version 2.30.0
ERROR: Unhandled exception: <b>CriticalError</b>:Failed to launch worker process:
Traceback (most recent call last):
File "site-packages\calibre\utils\ipc\server.py", line 197, in do_launch
File "site-packages\calibre\utils\ipc\__init__.py", line 19, in eintr_retry_call
File "multiprocessing\connection.py", line 147, in accept
File "multiprocessing\connection.py", line 416, in deliver_challenge
IOError: [Errno 232] The pipe is being closed


calibre 2.30 Portable isfrozen: True is64bit: False
Windows-7-6.1.7601-SP1 Windows ('32bit', 'WindowsPE')
32bit process running on 64bit windows
('Windows', '7', '6.1.7601')
Python 2.7.9
Windows: ('7', '6.1.7601', 'SP1', 'Multiprocessor Free')
Traceback (most recent call last):
File "site-packages\calibre\gui2\__init__.py", line 409, in dispatch
File "site-packages\calibre\gui2\actions\view.py", line 110, in book_downloaded_for_viewing
File "site-packages\calibre\gui2\actions\view.py", line 152, in _view_file
File "site-packages\calibre\gui2\actions\view.py", line 122, in _launch_viewer
File "site-packages\calibre\gui2\jobs.py", line 260, in launch_gui_app
File "site-packages\calibre\utils\ipc\server.py", line 214, in run_job
File "site-packages\calibre\utils\ipc\server.py", line 187, in launch_worker
CriticalError: Failed to launch worker process:
Traceback (most recent call last):
File "site-packages\calibre\utils\ipc\server.py", line 197, in do_launch
File "site-packages\calibre\utils\ipc\__init__.py", line 19, in eintr_retry_call
File "multiprocessing\connection.py", line 147, in accept
File "multiprocessing\connection.py", line 416, in deliver_challenge
IOError: [Errno 232] The pipe is being closed

This happens with any book I try to open, regardless of where I got it. The books still all open and run properly in the Kindle itself. I am running Windows 7.

Any help is appreciated!