In order to solve this problem permanently, suggest to change the SvrCfg.ini and delete the NrLog.txt too together. This is because if just deleting the fuke but didn't change the content of SvrCfg.ini, then the Nrsvr.exe after will still generate a NrLog.txt and grow up to similar size or even bigger. This log file record all the activities of the nrsvr.exe for future trouble shoot, but if don't want it then just configure nrsvr.exe don't generate log file, this will not affect dongle operation.
Remark : Please make sure you are using netrockey4 red dongle and not netrockey4nd brown dongle.
To edit SvrCfg.ini, please double click to open it in the part LogFile= (make it blank) then the log file is not created.
For example, the line is like this:
change it to this: