It has to do with the way the certificates were programmed in.
This fix will update your Mumble to version 1.2.3a and allow you to connect normally.
1.) Download this zip file (to somewhere that you can easily locate it). -*****Mumble Fix Zip File*****
2.) Open the mumble-1.2.3-resigned-binary.zip file (that you downloaded in step #1)
3.) Drag the enclosed Mumble.exe file into your Mumble folder, replacing the current Mumble.exe file. - (Choose the option to replace the old file)
4.) Log onto Mumble as you typically do and be happy.
Thanks, kirin1623, for the heads up.