Not sure what the keyexist's are for in that snippet you just posted. But since there wasnt even any IF/ENDIFs around them i dont think its doing any good. Try just something simpler like this.

Code:
;----- Run trackit audit
$InventFile = "C:\trackitaudit.id"
If Not Exist($InventFile) OR (SubSTR(GetFileTime($InventFile),6,2) <> SubSTR(@DATE,6,2))
   $null = WriteValue ("HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunOnce","TrackitAudit","\\na\netlogon\pcaudit\audit32.exe","REG_SZ")
EndIf