I have also a problem since today. The icon is gray, I try to log on, but I only see "Logged Out". After each login "Logged Out" appears again.
I am also having this issue on my PC. The Mac appears fine they should have it fixed soon for us.
Same problem here on a Wdos 7 machine.
Was working fine until last update
When thru the uninstall instructions and reinstall same problem
Just chatted with the tech support people and they walked me through solving this. Once I got computer literate took 2 minutes. Great people.
The same has been discussed in the below mentioned link:
You may also contact Customer/Chat support:
Let us know if this helps,