Kernel panic OS X Snow Leopard

Has anyone else experienced this problem? I've had trouble starting up a day.

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panic(cpu 1 caller 0x2abf6a): Kernel trap at 0x0022810d, type 13=general protection, registers:

CR0: 0x8001003b, CR2: 0x16d4bfb6, CR3: 0x00100000, CR4: 0x00000660

EAX: 0x086f53d4, EBX: 0x56c3e000, ECX: 0x085c5000, EDX: 0x00847e68

CR2: 0x16d4bfb6, EPB: 0x5d19bfc8, ESI: 0x081687c4, EDI: 0x085c5000

EFL: 0x00010006, EIP: 0x0022810d, CS: 0x00000008, DS: 0x00910010

Error code: 0x00002ed0

Debugger called: <panic>

Backtrace (CPU 1), Frame : Return Address (4 potential args on stack)

0x5d19bdd8 : 0x21b837 (0x5dd7fc 0x5d19be0c 0x223ce1 0x0)

0x5d19be28 : 0x2abf6a (0x59e3d0 0x22810d 0xd 0x59e587)

0x5d19bf08 : 0x2a1a78 (0x5d19bf20 0x27a317eb 0x5d19bfc8 0x22810d)

0x5d19bf18 : 0x22810d (0xe 0x56c30048 0x81150010 0x10)

0x5d19bfc8 : 0x2a179c (0c0 0cffffffff 0x2a17ab 0x81687a8)

BSD process name corresponding to current thread: kernel_task

Mac OS version:

10K549

Kernel version:

Darwin Kernel Version 10.8.0: Tue Jun 7 16:33:36 PDT 2011; root:xnu-1504.15.3~1/RELEASE_I386

System model name: iMac8,1 (Mac-F226BEC8)

System uptime in nanoseconds: 58151261649

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I have attempted restarting after each of the following without any success - most of the time hanging at 'system uptime in nanoseconds: xxxxxx)

1. Disconnected & reconnected power cord

2. Removed all cords, leaving only Apple keyboard and mouse connected

3. Reset PRAM (Cmd+Alt+p+r)

4. Safe boot (Shift)

5. Verbose (Cmd+V) - there were two error messages (below), hanging at 'waiting for remote debugger connection. kdp_poll: no debugger device'

Error 1

Error 2 registering socket filter (com.symantec.fw.ac.at). Your computer may not be fully protected

Application Control encountered an error while initializing. Your computer will not be fully protected.

Error 2

Running fsck on the boot volum...

Executing fsck_hsf (version diskdev_cmds-491, 6~3).

** Checking Journaled HFS Plus volume.

** Checking extents overflow file.

** Checking catalog file.

Incorrect block count for file live.0.indexArrays

(It should be 7038 instead of 3519)

6. Boot from original DVD (separate attempts, C and Option) - can't reach the Disk Utilitym, stalling on grey screen

7. Single user (Cmd+S) - 3 beeps and repeats

Any assistance would be greatly appreciated. Thanks.