Use of Acrobat Pro on a guest account is a violation of its license if you purchased a standard commercial version of Acrobat which is licensed for the use of a single user on a computer. If you have a site licensed version of Acrobat, then it probably is not an issue.
Can you please tell me the Operating Systems and Service pack version you have? Also can you please check if any Group policies are getting applied on your userB which make it a guest account (as was the case above for Peteo Seo).
Reseller