Hi,
Maybe you have got your M100 going thanks to Floh, but if after upgrading to 8.2.3 you still cannot open M100 and you have the encryption in order, maybe a repair disc permissions might be in order.
I have had to run it on just a few occasions, usually after a particularly nasty computer crash and it is not at all common so it may or may not apply to your situation.
I run Dual 2.0Ghz, 4Gb RAM, 10.3.9 and M100 8.2.2 for coming up to 3 years (but I am a 12 year M100 veteran and will be upgrading to HD Suite very soon)