Cannot connect by Computer Name

One of those things that worked fine, then all of a sudden it stopped working. I have 3 XP Pro machines in a workgroup (all have same workgroup name). I used to be able to connect with \\CompName but no longer can. I must connect by IP address now, \\192.168.0.10. This is intermittent too. Sometimes I can connect by name, but most of the time not. As there are no “servers”, I don’t know how to check for something similar to a DNS or WINS database. Help?