Random Spark problems on Windows 7

Has anyone else seen these problems with the Spark client on Windows 7 (64bit)

After logging in:

The user might or might not see the Contacts and Conferences tabs underneath the user list.

The user might or might not see the option to "Remove from roster" and/or "Remove user" when right-clicking a contact.

The user may or may not be able to search for other people.  When it fails it gives an error "Unable to find service"

In every case, these work in XP and Linux. As well as WIndows 7 after stopping and starting the Spark client a couple times.

This is a little embarrasing to push out to end users when it is so buggy...  If we can't resolve this we will need to use a different client.

Thanks

Bob