buffer overrun ?

[RAAF453_Shep]

well I have only seen it twice in the past week , but they were strange ..
I saw it once when the pc came back from screensaver mode, and my wife showed me once when she was playing at POGO .
I ran Adaware , and Spybot1.4 , both showed my system clean , and my AVG is up to date , and no viruses.
Has anyone else seen anything that would shed light on this ?
If it happened more than that , I would be nervous , I am fully updated at MS update.... but curious as to what caused it.
this pc has run flawlessly , and havent seen any symptoms , except with those 2 examples.

[RAAF453_Shep]

Microsoft Visual C++ Runtime Library

X Buffer overrun detected

Program: ...8C0CBB-084C-1033-0529-030515020001}\Update.exe

A buffer overrun has been detected which has corrupted the programs internal state. The program cannot safely continue execution and must now be terminated.

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I have only seen this now 4 times in the past week , but the system seems unaffected in its performance.