[REQ] A bit of CoD4 help

Well, it's simple: I get this error when running CoD4 multiplayer:

Problem signature:
Problem Event Name: APPCRASH
Application Name: iw3mp.exe
Application Version: 0.0.0.0
Application Timestamp: 4797d45e
Fault Module Name: iw3mp.exe
Fault Module Version: 0.0.0.0
Fault Module Timestamp: 4797d45e
Exception Code: c0000005
Exception Offset: 0017b380
OS Version: 6.0.6000.2.0.0.768.3
Locale ID: 1060
Additional Information 1: 8d13
Additional Information 2: cdca9b1d21d12b77d84f02df48e34311
Additional Information 3: 8d13
Additional Information 4: cdca9b1d21d12b77d84f02df48e34311

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I just got a legit Vista and installed CoD4 and ... bam! Error
I searched the web, did everything, no results. I went to some CoD4 forums, they told me to gtfo cuz I was a 'mod leacher' . So I have to settle with the *professional* opinion of MPGH members.