update:

We are not using any Object Qualifiers, so can safely rule that out.

I'm getting the same permission errors when upgrading DNN on development site from 6.1 to v6.2.

New logins have been created recently on our SQL2005 server (- prior to these upgrades, perhaps this could be the issue? -
although both sites are working as normal prior to upgrade attempts - unless the upgrades require further permission than the day to day operation of DNN sites?.)

If the problem is related to the below -  'insufficient database permissions'

Thought I'd cracked it, after a successful installation on the development server.

However I can't replicate the success on the live server and I could do with knowing what the errors mean so that I can get the live site working.
Therefor I rolled back the development server and tried to run this upgrade again - carefully tracing all steps exactly.

I now get the permission errors again and can't resolve them.

In SQL 2005 server >> Under programmability >> stored procedures >> 
the above items which give the errors, which say 'may not exist or don't have permission' for, exist in this list.

e.g
'grmApproveRepositoryObject'
'grmChangeRepositoryModuleDefId'
'Forum_ThreadViewsDelete

etc.. all appear in the stored procedure list.

Perhaps I need to Modify these stored procedures or add permissions somehow here? -
Although there's about 340 which failed.