Thank you for your post, I am sorry to hear that you have been seeing this problem.
Firstly, ensure that the logger actually connected to COM1 - ie, make sure it is not being called COM2 by Windows instead. Then check and make sure that the Enviromon software is addressing COM1. Also ensure that the software is configured corrrectly for the logger. If there is anything else installed to the COM1 port then this may be interfering with the deivce so uninstalling it or pointing it to a different port may help.
Let me know how you get on.