On a PLESK for windows installation, there was a problem reactivating websites, everything seems fine when you activate, then you refresh the page and it is inactive,
the answer is to first make sure the user is still active (date for user not domain name), then to activate the domains from the command line. Why ? not sure, but this is certainly still true for version 9 of plesk panel and soon i will be testing it for version 10.
domain.exe –on domainname.com
(Type it in yourself, and notice that — is 2 consecutive dashes)
You should see
SUCCESS: Changing status of domain ‘domainname.com’ completed.