I am running Windows 8 RTM and even since the RC I have had intermittent issues with Windows Live Messenger. I use this for messaging people at work at all hours of the day and for chatting with Facebook friends on occasion. After being signed in for more than a day in some cases, I find that even though my Status is set to Away, Busy, or Online I am appearing offline to everyone.
When I try to open and close Live Messenger I get an error, that says it cannot log me in Live network and asks me to Retry or Cancel. Retry always fails. In the error message there is an error code in the error details dropdown: 80010100
In order to get logged back in I had to open task manager and kill the “Windows Live Communications Platform (32 bit)” process:
After doing this I can now login without issue and I don’t have to reboot to do so.
Hope this helps someone who may encounter this same error message!