My problems seem to have started when I downloaded and played the latest 'Game for Gold', Lara Croft GoL, a few days ago. While playing single player and co-op I was experiencing a lot of what I'll call performance lag. I would have to wait up to 30 seconds for the game to catch up, with the music stuttering in the background even in areas where there was very little happening on screen at the time and occasionally the game froze completely or gave me a disc read error. First attempt to solve this was to delete and re-download the game...no good. Second was to consider overheating as the cause (It's quite hot in Australia atm) Aimed a fan at the xbox and opened a window behind it...no good. Third was to play something else and hope the problem went away, I fired up HAWX (another downloaded game running off the hdd) and noticed similar problems. Next I tried Borderlands 2 (disc) upon the game loading up, I was disconnected from xbox live. Not so an update could be done, just disconnected. Attempting to reconnect had me asked for my proofs email/password that, once supplied, led to an error message and code that I neglected to write down. The only way to reconnect was to Dashboard -> Sign out -> Sign in.
Back on the dashboard I saw new odd behaviour. Gamerpic replaced with grey box, avatar wearing old clothing, gamerscore sometimes displayed as actual, sometimes as 0 and the xbox taking minutes to boot up after a restart.
I came to the forums looking for information and tried the things I found here: Check cables and hdd installed properly, delete and download profile, clear system cache 3 times, clear content cache, reboot modem.
Things on the dashboard seem normal. I put in Skyrim and it asked me to update as expected. I put in Borderlands 2 and it didn't ask me to update, It got up to the "Searching for DLC" part of the startup before freezing and giving a disc read error twice. Third time it still didn't try to update but I managed to load up one of my games anyway :S HAWX and GoL still experiencing performance lag but haven't crashed yet.
My next problem concerns Assassins Creed 3. Trying to play this brings up an error saying "This game requires an update but the update couldn't be found" and returns me to the dashboard.
Apologies for the wall of text but I wanted to make sure I listed everything in case anyone recognises the telltale signs of a hdd about to fail or something.
Any insight would be appreciated.