CommandPromptPortable won't open to path on other drive

Hi all,
I'm tring to crate a portable "command prompt here" context menu entry using CommandPromptPortable & PortableFileAssociator, but for some reason CommandPromptPortable won't open to a drive other than its own.

Executing "j:\portableapps\commandpromptportable\commandpromptportable.exe j:\documents" opens the CLI to that folder, while "...commandpromptportable.exe c:\windows" opens the CLI to "j:\".

Also, executing "...commandpromptportable.exe %temp%" or other variables causes it to open and close immediately.

Is there a way to fix this?
Thanks

EDIT: I attempted to use CHDIR's /d switch (...commandpromptportable.exe /d c:\windows) and got the same result as with the variables.