You're asking a few different questions here. Let me try and answer them individually:
Act emarketing error: This can sometimes be solved by simply clicking Log Off in the Emarketing menu, and then clicking Log On to sign back in, then click Refresh from the View menu.
Becoming logged out of the web interface: This can be caused by some invalid data in a particular record. If this is occurring on an Act Premium Cloud account, I would suggest contacting our support team for this issue so that our Cloud team can investigate the cause.
Version showing as v18.1 on web interface: Act Premium Cloud servers are all currently running Act v18.1. The next update for them will be to v19.
Are you hosting the server where it is showing v18.1 on the web interface, but can confirm the installation is v18.2? If so, we are aware of a defect where if the installation of APFW was upgraded from an older update, then the pre-upgrade version number will be shown.