xbox live is up and running except for the marketplace which says some people may experiance problems.
http://support.xbox.com/support/en/us/nxe/xboxstatus.aspxRemember GOOGLE is your friend I had a browse around and this is what i found
Steps to Try and Fix 360 Freezing at Start-up
1) Turn off your Xbox 360 and physically disconnect it from the internet by either unplugging the ethernet cable or disconnecting the wireless adapter.
2) Turn on your Xbox 360 and sign into your account. You should NOT be connected to Xbox Live.
3) Navigate to the "System" blade and choose the "Memory" option, then select your storage device.
4) Now search. Look through all the system folders then find and delete ALL incomplete content files. You can spot an incomplete file by the yellow exclamation point icon. Remember to delete ALL incomplete files
5) Once all the incomplete content files have been deleted, turn off your Xbox 360.
6) Reconnect your Xbox 360 to the internet by plugging back in the ethernet cable or wireless adapter.
7) Turn on your Xbox 360, connect to Xbox Live and hopefully your problem is solved.