Is there a problem with Joomla 1.7.1 and Virtuemart 2.0 G or H? When you check the forum its seem certain file are not getting installed or problem with the menu. I do know when doing an upgrade in Joomla 1.7.1 it fails to add a admin menu item or a menu to the front sometimes. Which will require you to edit your database directly and then do a re-install on the component you are upgrading.
So why so many little problems when it comes to Joomla 1.7.1? And yes I know you guys are still working on getting a stable version out.
There appears to be a bug Joomla 1.7.1 (not VirtueMart). I just had the problem too, that a Joomla extension told me "Installed successfully" but never showed up in the extension menu. Apparently J1.7.1 sometimes doesn't handle the extension and menu ids correctly. After uninstalling the component, I had to delete the component entries in the J1.7.1 Extensions and Menu tables manually, before another attempt to install the component also displayed the menu item for the component.