I had a strange problem with installing Virtuemart 2.0.3#. It reported succes and worked fine but did not appear in the admin components menu. I dived into the database and found that it had a clash with the XMap extension (version 2.2.1). The Virtuemart entry in the #_menu table used an ID which belongs to a XMap virtuemart plugin (which has a lower ID in my #_extensions table). Replacing the ID with the correct Virtuemart #_extensions ID did the trick. What is the cause of this mixup, is this a Joomla, XMap of Virtuemart issue/error/bug? Who's permanent fix is this?
I'am using Joomla 2.5.3, on Windows XAMPP as test environment with MySQL 5.5.16 an PHP 5.3.8.
Same problem here on Joomla 2.5.4 and Virtuemart 2.0.6 running on a LAMP server.
I also have Xmap installed which was the key to the solution for me:
Log in to the back end, components menu, Xmap, Extensions tab: Xmap - Virtuemart Plugin <<< enable this plugin.
Then look in the Components menu it's there. ;D
Thanks to liquorice for pointing me in the right direction 8)
Same thing just happened to me when installing VM 2.10 on Joomla 2.5.6. I also have Xmap installed, so I took stafford's advice and enabled the plugin. As soon as the plugin was enabled, VM showed up in the admin menu.
The solution is here (with or without Xmap): http://forum.virtuemart.net/index.php?topic=101120.msg336673#msg336673