Stelian, please take a look at the backtrace below... does it ring any bells?
it probably happens when a connection times out, or in some unusual situation. please not the "unconnected" part in the socket's print-object output...
("nafi" "http worker 5 / LEVEL-1-ERROR-HANDLER" 2008-12-05T00:34:27.217601+01:00 HU.DWIM.WUI::WUI +ERROR+ " *** At: 2008-12-05T00:34:27.203581+01:00 *** In thread: http worker 5 / LEVEL-1-ERROR-HANDLER *** Error: Unhandled memory fault at #x0. *** Backtrace is: 000: ((LAMBDA (ERROR)) #<SB-SYS:MEMORY-FAULT-ERROR {100B380821}>) [:EXTERNAL] 001: ((LABELS HU.DWIM.WUI::LEVEL-1-ERROR-HANDLER) #<SB-SYS:MEMORY-FAULT-ERROR {100B380821}>) 002: (SIGNAL #<SB-SYS:MEMORY-FAULT-ERROR {100B380821}>) [:EXTERNAL] 003: (ERROR SB-SYS:MEMORY-FAULT-ERROR) [:EXTERNAL] 004: (SB-SYS:MEMORY-FAULT-ERROR) 005: (SB-SYS:MEMORY-FAULT-ERROR) [:EXTERNAL] 006: ("foreign function: #x41E9B2") 007: ("foreign function: #x41EA70") 008: ((CLOSE :AROUND (IO.STREAMS:DUAL-CHANNEL-GRAY-STREAM)) #<active IPv6 stream socket, unconnected {100B04A221}>) [:EXTERNAL] 009: ((CLOSE :AROUND (IO.STREAMS:DUAL-CHANNEL-SINGLE-FD-MIXIN)) #<active IPv6 stream socket, unconnected {100B04A221}>) [:EXTERNAL] 010: ((CLOSE :AROUND (NET.SOCKETS:SOCKET)) #<active IPv6 stream socket, unconnected {100B04A221}>) [:EXTERNAL] 011: (HU.DWIM.WUI::CALL-WITH-SERVER-ERROR-HANDLER #<CLOSURE (LAMBDA #) {100B37FAA9}> #<active IPv6 stream socket, unconnected {100B04A221}> #<CLOSURE (LAMBDA #) {100B37FAC9}>) 012: ((FLET #:CLEANUP-FUN-[WORKER-LOOP/SERVE-ONE-REQUEST]634)) [:CLEANUP]