Back in 1998, Mark Russinovich developed code that
uses the Native API to create registry keys that
are inaccessible using the Win32 API by embedding NULs
in the key names. The utility, REGHIDE, includes source
and is available at:
The code works because the Native API describes a
name based on the number of Unicode characters,
so NUL is valid. However, the Win32 API treats a
NUL as end of string, rendering the key inaccesible
to regedt32 and regedit.
Based on your description of the problem, this may
not be the issue however.