Version num doesn't match d/l? & Error when clicking Add Books

[callahan09]

So this morning I downloaded & installed version 2.51.0 when the program prompted that there is an update.

Then I clicked AddBooks and got THIS error:

ZipImportError: can't find module win32com

So I uninstalled the program entirely and re-downloaded it and installed it.

NOW, I downloaded by clicking "download calibre" on this page:
http://calibre-ebook.com/download_windows

It says it should be version 2.51.0.

But when I open the program and click Preferences, it actually shows version 2.43.0? What's up with that?

And while I'm not getting the same error as before, when I click Add Books, I still get an error:

IOError:zipimport: can not open file C:\Program Files\Calibre2\pylib.zip

calibre, version 2.43.0
ERROR: Unhandled exception: <b>IOError</b>:zipimport: can not open file C:\Program Files\Calibre2\pylib.zip

Traceback (most recent call last):
File "site-packages\calibre\gui2\actions\add.py", line 424, in add_books
File "site-packages\calibre\gui2\__init__.py", line 761, in choose_files
File "site-packages\calibre\gui2\__init__.py", line 672, in __init__
File "site-packages\calibre\utils\filenames.py", line 508, in expanduser
File "site.py", line 50, in load_module
IOError: zipimport: can not open file C:\Program Files\Calibre2\pylib.zip

What can I do about this? Why is it saying I installed version 2.43.0 when the download site says the current version is 2.51.0? Please help! Thanks in advance.

EDIT: UPDATE: I have tried uninstalling & reinstalling numerous times now. I even went to the download past versions page and downloaded 2.51.0 64-bit from there (I have 64-bit Windows 10 home edition OS). It still says version 2.43.0 in the program and actually gives me the win32com error again. I then downloaded an older version, 2.50.0 64-bit, and it too is giving the same error and says version 2.43.0. I'm tempted to try downloading version 2.43.0 and see if that works! For all I know, that might have been the last version I had installed before trying to update it this morning. I can't be sure, but it was probably back around November the last time I updated the program.

What's going on here???

EDIT 2: I found this post:

https://bugs.launchpad.net/calibre/+bug/907058

I added the folder to my Windows Defender exclusions list, uninstalled & reinstalled again, and all the same problems are still there.

EDIT 3: I went ahead and tried installing version 2.43.0. THIS version works. I've added the books I wanted to add. I'm not going to bother trying to update the software again until I hear a response here that could explain why this is happening and how I can get the updated versions to work. So for now, I'm sticking with version 2.43.0, and hopefully the issue I'm having does get figured out sometime.

[theducks]

What was IN the filename you downloaded?
2.51.msi should be part of the name.

Was Calibre fully shutdown when you launched the MSI?

Do you have a (modern) 64 bit computer? You are currently downloading (the link you supplied) the 32 bit version, but you may be launching the older 64bitm install (both CAN exist at the same time on your system

64bit will show next to the version number in calibres status bar