Solaris 2.4 has a combination of problems that make running with quotas of or with near-full disks almost impossible. The problems include writing message to /dev/console, which requires switching of interrupts and make the machine appear dead, clients caching upto 2MB of failed writes and retrying them, hammering the server to death.
Fix: kernel patch 101945-32 (sparc)/101946-29 (x86) or later. Needs to be applied on clients as well as servers.