amin panel kick out

dear all
i have installed nop commerce on a shared server (brinkster) all works good, however when i login to the admin panel i get kicked out during the session and after. it does not keeping me logedin. takes about 10 to 30 sec and i have to login again.

i also get the following when i use different admin email
Validation of viewstate MAC failed. If this application is hosted by a Web Farm or cluster, ensure that <machineKey> configuration specifies the same validationKey and validation algorithm. AutoGenerate cannot be used in a cluster.

please help

thank you

by the way u have an amazing product

hi again followed https://www.nopcommerce.com/boards/t/7119/avoiding-error-message-validation-of-viewstate-mac-failed.aspx

and it works fine

thank u