OS X Quirks

[Rod Clifford]

I have recently begun having problems with OS X startup:
User fonts/OS 9 fonts do not load/ Mail will not launch. Other apps 
(Illustrator, iTunes) still work.
Repaired permissions using installation CD last week but problem has 
started again a couple of days later.
Login out & back in sometimes fixes it, worst case a restart is 
required. Once logged out and the "Welcome
to Darwin" login screen came up. This behavior is also on a G4 DP 
machine here at the office.
Any guesses, or pointing me to a web site that may have a solution 
would be appreciated.
I have looked at a couple of sites for a similar behavior problems but 
found nothing.  TIA Rod