It's almost certainly a problem with your PC. I suggest the following:
Do a full system scan with an anti virus program.
Do a surface scan of your HDD
Run a malware checker like Malwarebytes
Run the "Clean up your PC" program and delete temp files etc...
Completely uninstall the Kobo desktop software and delete any directories associated with the program. Then reinstall.
I'm not a support person with Kobo, but if I was having the problems you're having. I would try all that.