Office 2008:Mac Excel Problem

I installed Office 2008 on my MacBook Pro, 2.4 GHz Intel Core 2 Duo, 4 GB 667 MHz DDR2 SDRAM, running a clean install of Leopard Version 10.5.1 last night because I wanted to update an address database that I had created with the 2004 version. I had saved the file as a txt file so I could access it with my mail merge program. Excel opened the file with no problem but when I started entering data is suddenly quit without saving any of the data. I reopend the program and saved it as an Excel doc and started entering the data again--the same thing happened.

Has anyone else had this problem.

Thanks,

Jean