I had this problem when upgrading a NetWare server from SP3 to SP6, and
it's also happened on one that went from SP3 to SP7.

After the SP is applied, iPrint client on the server is upgraded. Next
reboot, workstations pop up a dialog that says there is a newer iPrint
client on the server, do you want to upgrade? User clicks OK, 20-30
seconds go by, then you see an error dialog "The iPrint client cannot be
installed at this time". Strangely enough, can't find anything on the
knowledgebase about this, and there doesn't seem to be much in the
forums. But I've had this happen on three servers so far. Manually
installing the iPrint client from the server works fine, so I don't
understand what's going wrong. All the servers in question had SP3
originally, so they are iPrint 4.05 I believe.

Is there any fix to this other than manually installing the client?