Cannot Log In to my account front office

[pvr]

Hi,

I've just upgraded to v1.2

When i create a new account it works fine.
Then i log out, and try to log in for the 2nd time and nothing happens.
The screen gets stuck with the following address .......
........Cannot find "http://www.domain.com/shop/authentication.php?back=my-account.php"

Also, i tried buying a few products as virtual downloads, and i'm sent an email confirming the order. When i click on the link to download them, and linked to my presta site to log in... the log in fails at the same location...

I tried in firefox 3.5 and ie8.

Should i Re-install...again

Any help appreciated.???