sudden reboot

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When I press a key to exit from an automatic standby Computer has gone to screen saver, then blank (black) screen [normal], and then to the blinking light in the power switch. - (pressing a key usually turns on the screen to previous state), instead the computer reboots instead of just waking up.

The system error log is copied below.

This has happened twice in the last couple of days.

How to fix??

---copy--
Event Type: Error
Event Source: System Error
Event Category: (102)
Event ID: 1003
Date: 1/26/2007
Time: 11:12:13 AM
User: N/A
Computer: GEORGENEW
Description:
Error code 1000000a, parameter1 917e68ec, parameter2 00000002, parameter3 00000000, parameter4 8050e07a.

For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.
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 30 1000000
0020: 61 20 20 50 61 72 61 6d a Param
0028: 65 74 65 72 73 20 39 31 eters 91
0030: 37 65 36 38 65 63 2c 20 7e68ec,
0038: 30 30 30 30 30 30 30 32 00000002
0040: 2c 20 30 30 30 30 30 30 , 000000
0048: 30 30 2c 20 38 30 35 30 00, 8050
0050: 65 30 37 61 e07a

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