HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management\PrefetchParameters
the key "enable prefetcher" on mine is set to value 3 which is "prefetch all"
has this value changed in your registry ?
the values used in windows
prefetch are :
0 - Disable Prefetch in Windows
1 - Prefetch only Application Launch files
2 - Prefetch only Boot files
3 - Prefetch all
Nobody is perfect, but I'm pretty fucking close!