As you probably realise 163 and 173 means that the box is losing setup information. Changing the CMOS battery (I assume that is what you changed) is a good start. However the Hardware Maintenance Manual has a a really good diagnostic procedure. Assuming that you don't have a manual, you can download one from: www.lenovo.com. (Lenovo own all of IBM's PC assets now.)
Terry, May 2006