Sandboxie 3.72 64 bit Win7 7601 SP1 64 bit
installed windows sdk, checked "update path variable"

in real registry
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Session Manager\Environment
PATH has
%SystemRoot%\system32;...;
and

in sandbox
HKEY_USERS\Sandbox_user_mysandbox\machine\System\CurrentControlSet\Control\Session Manager\Environment
PATH has
%SystemRoot%\system32;...;C:\Program Files\Microsoft Platform SDK for Windows Server 2003 R2\Bin\.;C:\Program Files\Microsoft Platform SDK for Windows Server 2003 R2\Bin\WinNT\.

but when i run cmd.exe->"set"
i got same variables inside and outside sandbox

Are you saying that you installed it inside a sandbox?

The Start.exe program is responsible for picking up environment variables from the sandbox registry. Perhaps you start that cmd.exe without going through Start.exe, somehow?

sorry, cannot reproduce. rebooted - all ok.

it also wasn't possible to delete sandbox, because of RegHive* were locked (other files deleted successfully and no program were running insideas sandboxie control showed).
inside registry few keys (as i mentioned above, "HKEY_USERS\Sandbox_user_mysandbox\machine\System\CurrentControlSet\Control\Session Manager\Environment) culdn't be deleted through regedit manually.
quite strange, because it happens 3 times at a row.

maybe i got some hanging programs (cmd.exe for example) inside sandbox that wasn't shown inside sandboxie control tree (it happens with me several times in older versions like 3.42).

rebooted - all ok.
thanks TZUK!