the cause for the problem could be identified and the next BoxCryptor for Windows version will contain a fix for it. Until it is available there are three workarounds:
1) In our tests, it seems the problem does not occur if the BoxCryptor drive is mounted _before_ the Malwarebytes Anti-Malware service. If BoxCryptor is configured and autostarted, setting the startup type of the MBAMService to "Automatic (Delayed)" helped in most cases.
2) Uninstall Malwarebytes Anti-Malware or disable its MBAMService.
3) Go back to the latest BoxCryptor for Windows v1.2 version until the new v1.3 version is available. You can download it here: http://www.boxcryptor.com/download/BoxCryptor_v220.127.116.11_Setup.exe
Sorry for the inconveniences. We'll release the new version asap.