PC restarting due to ntoskrnl.exe

[zshy88]

*** WARNING: Unable to verify timestamp for ntoskrnl.exe
Windows XP Kernel Version 2600 (Service Pack 2) MP (2 procs) Free x86 compatible
Product: WinNt, suite: TerminalServer SingleUserTS
Kernel base = 0x804d7000 PsLoadedModuleList = 0x8055c700
Debug session time: Sun Jan 6 02:59:20.515 2008 (GMT-8)
System Uptime: 0 days 5:27:25.234
Unable to load image ntoskrnl.exe, Win32 error 0n2
*** WARNING: Unable to verify timestamp for ntoskrnl.exe


this is what showed up in the debug tool

anyone have any idea how i can fix it ? or what is causing this problem ?

thank you all very much in advance!