Associating quotes, projects, clients to e-mails manually | Messages tab

I have an on-going (and unfortunately long-standing) ticket with the HelpDesk about this, but I am wondering if everyone is having the same difficulties as we are.

We like having project related messages easily accessible in the Messages tab of a quote/project/task/etc. It's a great way for anyone who wants to know more about the project (especially what was communicated with the client) to quickly catch up with everything. This works fine with messages the system associates automatically. However, when we try to associate e-mails manually from the CRM > Mailboxes section, the process crashes.

Has anyone had this problem and figured out a way around it?