I'm having serious issues with Cydia. I keep getting errors like "the following signatures were invalid" or I get some "size mismatch" error. I dunno what's causing this problems but I'm guessing my verision of ios is too outdated. So since I'm on 4.2.6 and never upgraded since I got my iPhone is it too late for me to upgrade to another version and jailbreak again? I'm having a bunch of other issues too like my phone keeps crashing and just becomes totally unresponsive, I think I just really need a format and fresh install.