Upgrade to 8.5.1 - Mail Database

Hi

we are running Notes 8.0.2 standard in our Citrix environment. We are currently moving to 8.5.1 standard and have one of the 5 servers upgraded already. When I move a user to the new server everything seems to work correctly (the new client is started, the local databases are updated and the client is displayed). The problem is that SOME users do not see anything in their Mail view (ie. they see the horizontal and vertical lines in the database but no outline on the left and no documents on the right side of the window) and almost all have the same problem when they open the to do view. What we do to fix this is delete cache.ndk, desktop8.ndk and the whole workspace subdirectory. Does anybody have a better solution for this problem, I would like the upgrade to go smoothly and not need this workaround!

Thanking you in advance

Ursus