XP will not allow Windows 8 to connect to share

I was using Windows 8 to connect to XP and suddenly it stopped. I can connect from XP to Windows 8 and I can use remote desktop from either machine. I have reset the wireless router. I also have a tablet with Windows 8 and it connects to the PC and not the XP.

The dialog for the XP pops up, but will not allow the connection - user name or password wrong. When this initially started, the XP would not connect to Windows 8 saying the certificate was bad. I started looking and the time on the XP was wrong and changing it solved the problem of connecting from the XP to windows 8.

Answer to this problem was that the display time and the CMOS time on the XP machine were 3 months off. When set to the correct date and time, everything worked. Guess I need to take a look at the CMOS battery on the 10 year old machine.