[maxmsp] Jitter doesn't open any more! Help!

Hi everybody,
all in a sudden Jitter doesn't work any more! And in the middle of a  
project!
I use MaxMSP 4.6.3 an iMac Intel with OS X 10.4.10... today when I  
started to work all the jitter external where no more accessible from  
my patches...
Is it maybe because yesterday night I upgraded the OS to the last  
security upgrade? I hope not!!!
Moreover, following my panic I tried to reinstall Jitter and... it  
is  no more possible! It says that I can't installi it because I need  
MaxMSP 4.6, that I have...
What should I do?
Please help!!


massimiliano