No results found after regkey change

I decided to clear pagefile.sys so I set HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Session Manager\Memory Management\ClearPageFileAtShutdown to 1 and rebooted OK. However Recuva in standard scan now runs stage 1, with the number of files found increasing as normal, but ends immediately in stage 2 with No Files Found.

In debug mode this appears in the log: WinAPI exception: FileDriveImpl.cpp(140) : The parameter is incorrect.

I have reset the registry key back to 0 and rebooted and the same happens, no files found.

I knew I should have kept my fingers out of the registry!

Well, would you believe it, it started to work again this afternoon. I remember having the same problem on the initial install of this release Recuvca, and that righted itself. Very peculiar.

I don't have a winapi file in the Recuva folder (but I have a winapp in CC's folder). Should I have one?