Windows crashes with error code 0x000007E

Hi, I was hoping someone could help, my pc starting randomly rebooting on Saturday morning, at irregular intervals. The error code reported on the BSOD was 0x0000007E (0xc0000005, 0x804EF2F4, 0xF7A5FA60, 0xF7A5F75c).

The event viewer shows:

Event Type: Error
Event Source: System Error
Event Category: (102)
Event ID: 1003
Date: 03/11/2008
Time: 16:03:02
User: N/A
Computer: DMC-470C1ACB3D5
Description:
Error code 1000007e, parameter1 c0000005, parameter2 804ef2f4, parameter3 f7a73a60, parameter4 f7a7375c.


Data:
0000: 53 79 73 74 65 6d 20 45 System E
0008: 72 72 6f 72 20 20 45 72 rror Er
0010: 72 6f 72 20 63 6f 64 65 ror code
0018: 20 31 30 30 30 30 30 37 1000007
0020: 65 20 20 50 61 72 61 6d e Param
0028: 65 74 65 72 73 20 63 30 eters c0
0030: 30 30 30 30 30 35 2c 20 000005,
0038: 38 30 34 65 66 32 66 34 804ef2f4
0040: 2c 20 66 37 61 37 33 61 , f7a73a
0048: 36 30 2c 20 66 37 61 37 60, f7a7
0050: 33 37 35 63 375c

Can anyone shed any light on the likely cause of this?

Comodo firewall is the problem. It's very new, when did you install it?

BugCheck 1000007E, {c0000005, 804ef2f4, f7a73a60, f7a7375c}
Probably caused by : cmdguard.sys ( cmdguard+e0c7 )
Image name: cmdguard.sys Timestamp: Thu Oct 23 05:33:24 2008 (48FF8E14)

Been using it for a while, but recently updated it.