It seems that there is a problem with the server's log file. There are two ways to solve this. One is to wait till tomorrow to log in because MSDSpro will just create a new log file for that new day.

Or you can go to your MSDSpro server folder in the program files. And delete the problematic log file.

To do this, you need to open the MSDSpro server folder in the program files. Then you need to look either under

SERVER DATABASE--> LOGS--> SYSTEM--> Then you will see a text file, delete that text file

OR

PROGRAM--> LOGS--> SYSTEM--> Then you will see a text file, delete that text file

That text file that you just deleted is the log file with an error.

Now when you next open up MSDSpro, it should create a whole new log file, and allow you access,