Thank you for your very swift response - excellent.
Installation went without errors - and when I took the defaults and just enabled Virtuemart it showed the Calculation Check on the Your Account page perfectly but then failed with "You failed the spam check. Please try again!"
I tested a few times with same result.
I understand that you don't want to provide support for this old version - so I'll see if I can work it out.
I disabled everything else as you suggested (so I disabled Hidden Field & Time Lock) - and then when I tested I got: "Invalid Token, while trying to save user". Then I remembered reading in this forum that this error can be fixed by disabling "Encrypt All Input Fields" - so I disabled.
You should reactivate the other two options and test again. This would increase the level of security. Another good tip is to use Akismet (you can even use it with a free account). With this constellation I have not received any spam registrations on a special test domain for years!