If you're talking about the Flash files, that's something that has to be signed to your individual PSP, if I recall correctly.
Grab this program and get into the Recovery Menu. Use the USB linkup to put it and the 5.00 OFW update EBOOT on your MemCard, then use the option to run it from the Recovery Menu.
You'll lose your settings, but it'll put a fresh re-install of 5.00M33-4 on your PSP.
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