After installing Equitrac Office / Express 5.7 the folder C:\ProgramData\Microsoft\Crypto\RSA\MachineKeys keeps growing in size. This issue has been seen on Windows Server 2012 R2.
This issue is caused by the Equitrac DCS service not having the required components installed. This will cause DCS service to continuously restart, causing the C:\ProgramData\Microsoft\Crypto\RSA\MachineKeys to grow in size.
In the Add roles and services wizard, install the ASP.net 4.5 feature from the .NET Framework 4.5 section