MemoryContextAlloc: invalid request size

Our customer is reporting a database problem after they ran into a
disk quota/filesystem full situation.

This is Postgres 7.2.x on Solaris.
The database server starts without any obvious errors, but the app. Server
cannot establish connection. (It is setup to use Unix Domain Socket)

I did not have a chance to see the database-log, but we have the error-log
and
the truss log from the App. Server.

In the error-log I see this:
... ...
Connection to database failed
FATAL: MemoryContextAlloc: invalid request size 0

And this in the trace log:
... ...
10894: open("/usr/lib/libresolv.so.2", O_RDONLY) = 11
10894: fstat(11, 0xFFBE9004) = 0
10894: mmap(0xFE020000, 8192, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_FIXED,
11, 0) = 0xFE020000
10894: mmap(0x00000000, 303104, PROT_READ|PROT_EXEC, MAP_PRIVATE, 11, 0) =
0xFDD20000
10894: mmap(0xFDD64000, 15564, PROT_READ|PROT_WRITE|PROT_EXEC,
MAP_PRIVATE|MAP_FIXED, 11, 212992) = 0xFDD64000
10894: mmap(0xFDD68000, 2728, PROT_READ|PROT_WRITE|PROT_EXEC,
MAP_PRIVATE|MAP_FIXED|MAP_ANON, -1, 0) = 0xFDD68000
10894: munmap(0xFDD54000, 65536) = 0
10894: memcntl(0xFDD20000, 33536, MC_ADVISE, MADV_WILLNEED, 0, 0) = 0
10894: close(11) = 0
10894: munmap(0xFE020000, 8192) = 0
10894: so_socket(1, 2, 0, "", 1) = 11
10894: fstat64(11, 0xFFBE8A70) = 0
10894: getsockopt(11, 65535, 8192, 0xFFBE8B70, 0xFFBE8B6C, 0) = 0
10894: setsockopt(11, 65535, 8192, 0xFFBE8B70, 4, 0) = 0
10894: fcntl(11, F_SETFL, 0x00000080) = 0
10894: connect(11, 0x0060EAA0, 77, 1) = 0
10894: poll(0xFFBE89E8, 1, -1) = 1
10894: sigaction(SIGPIPE, 0xFFBE8788, 0xFFBE8888) = 0
10894: send(11, "\0\001 (\002\0\0 s y n c".., 296, 0) = 296
10894: sigaction(SIGPIPE, 0xFFBE8788, 0xFFBE8888) = 0
10894: poll(0xFFBE89E8, 1, -1) = 1
10894: recv(11, " R\0\0\0\0 E F A T A L :".., 16384, 0) = 58
... ...

Could you recommend the remedy?

Thanks in advance,
Mike.