Balloon Messages

I have two computers.One is Two years old the other one year old
Both have the same programs loaded and both have the latest CIS(RC 1)
On the latest one i have never been able to get “balloon messages” to work although they work perfectly on the older machine.
I also have two hard drives in the latest machine ,one with XP Home the other with Windows 7 and “balloon messages” work with Windows 7.
I can’t figure it out.
Any suggestions please