From what Google tells me, the reason why this is a REG_EXPAND_SZ string probably is simple: It can use environment variables.
It is also null terminated, which might be another difference to REG_SZ.
You will probably also run into permission problems; only administrators are allowed to change that registry value (you can verify this with REGEDT32.EXE instead of REGEDIT.EXE).
It is also null terminated, which might be another difference to REG_SZ.
You will probably also run into permission problems; only administrators are allowed to change that registry value (you can verify this with REGEDT32.EXE instead of REGEDIT.EXE).