My 9 month old graded T2 running CF2.17 has just booted and informed me that the disc needs formatting!? I've exercised the on-screen option to test the disc but am yet to reformat. Is anything else to be attempted first?
Upgrade it to the latest CFW then use telnet (http://wiki.hummy.tv/wiki/Telnet) to get access to it and choose to restart in maintenance mode. Once in maintenance mode, connect via telnet again and choose option 1 (check and repair disk). It might be able to fix it automatically or you might need more help but you should be able to get everything back.