[X4U] mystery event in the night

[Jan Melichar]

All was well when I left the computer (G5 running 10.4.4) at the end  
of the day. The next morning it was unwilling to do anything. No  
amount of disk repair via installation CD or Diskwarrior tender  
attention did anything to bring it to life.It would not start up  
beyond that dull grey apple. Anyway to cut a long story short it's up  
and running now but I wonder if anyone could throw some light on this  
mystery event.

Over a half hour period in the middle of the night (modification date  
were the clue) most non apple application disappeared from their  
folders and those that did not showed generic icons and did not work.  
It would be good to know what caused this if only to try and avoid it  
happening again.

Anyone any idea?

Jan