We are using 11.1.0.7 Standard Edition One on Windows 2003 32 bit - with the 3G switch enabled. In the last 4 days, one of our sites has had 2 downtimes where Oracle has stopped accepting new connections and existing ones have stopped working. Nothing that we are aware of has changed in the OS, Oracle or application. The error in the alert log is like Exception [type: ACCESS_VIOLATION, UNABLE_TO_READ] [ADDR:0x0] [PC:0x7C82A774, {empty}] Errors in file d:\oracle\diag\rdbms\abcd\xyz\trace\xyz_ora_3220.trc (incident=54056): ORA-07445: exception encountered: core dump [PC:0x7C82A774] [ACCESS_VIOLATION] [ADDR:0x0] [PC:0x7C82A774] [UNABLE_TO_READ] [] ORA-03135: connection lost contact The first argument doesn't contain a function name. On the first occasion, the database stayed working for 57 minutes and through 3 scheduled archive log swaps. Then more errors like following and connections now hung: Exception [type: ACCESS_VIOLATION, UNABLE_TO_READ] [ADDR:0x0] [PC:0x7C82C873, {empty}] Errors in file d:\oracle\diag\rdbms\abcd\xyz\trace\xyz_ora_3480.trc (incident=54064): ORA-07445: exception encountered: core dump [PC:0x7C82C873] [ACCESS_VIOLATION] [ADDR:0x0] [PC:0x7C82C873] [UNABLE_TO_READ] [] Incident details in: d:\oracle\diag\rdbms\abcd\xyz\incident\incdir_54064\xyz_ora_3480_i54064. trc Sat Nov 06 07:57:51 2010 Exception [type: ACCESS_VIOLATION, UNABLE_TO_READ] [ADDR:0x0] [PC:0x7C82C873, {empty}] Errors in file d:\oracle\diag\rdbms\abcd\xyz\trace\xyz_j000_1596.trc (incident=54072): ORA-07445: exception encountered: core dump [PC:0x7C82C873] [ACCESS_VIOLATION] [ADDR:0x0] [PC:0x7C82C873] [UNABLE_TO_READ] [] Incident details in: d:\oracle\diag\rdbms\abcd\xyz\incident\incdir_54072\xyz_j000_1596_i54072 .trc Sat Nov 06 07:59:57 2010 kkjcre1p: unable to spawn jobq slave process On the second day this happened (2 days after the first) the instance hung at the time of the first message in the alert log. This time the message was very similar: ORA-07445: exception encountered: core dump [PC:0x7C84D0B3] [ACCESS_VIOLATION] [ADDR:0x2A] [PC:0x7C84D0B3] [UNABLE_TO_READ] [] The actual dump files contain the message Symbol file d:\oracle\product\11.1.0\db_1\BIN\oracore11.SYM does not match binary But I'm not sure about the relevancy of this. We've logged a SR, but in the meantime thought I'd ask the list if others have seen errors like this, or for suggestions on what information to gather next time? Thanks for your time, Bruce Reardon bruce.reardon@xxxxxxxxxxxx