[SOLVED] Invalid Token, while trying to save user

[mySITE4u]

VirtueMart 2.0.20

While trying to open Shopping cart I get message 'Invalid Token, while trying to save user' with a blank page.
Before it worked and showed Shopping cart.

Also Rupostel OPC is installed on a site.

What is the issue?

[jenkinhill]

VM2.0.20 is over two years old!

See http://forum.virtuemart.net/index.php?topic=120500.0
http://www.rupostel.com/phpBB3/viewtopic.php?f=5&t=816
http://forum.virtuemart.net/index.php?topic=102879.msg344169#msg344169

[mySITE4u]

VM2.0.20 is over two years old!

See http://forum.virtuemart.net/index.php?topic=120500.0
http://www.rupostel.com/phpBB3/viewtopic.php?f=5&t=816
http://forum.virtuemart.net/index.php?topic=102879.msg344169#msg344169

Thanks!

The issue was Artio SEF.
I don't know why but they make many sef urls which are the same, say:

shopping-cart -  index.php?option=com_virtuemart&view=cart&Itemid=282
shopping-cart -  index.php?option=com_virtuemart&controller=opc&task=checkout&view=opc&Itemid=282
shopping-cart -  index.php?option=com_virtuemart

So that when I try to open my cart www.mydomain.com/shopping-cart it redirects me to wrong url ( index.php?option=com_virtuemart&controller=opc&task=checkout&view=opc&Itemid=282) and this causes the issue.

I've just renamed:
shopping-cart to shopping-cart-opc for index.php?option=com_virtuemart&controller=opc&task=checkout&view=opc&Itemid=282
and
shopping-cart to shopping-cart-vm for index.php?option=com_virtuemart

That's it.