GA-MA78G-DS3H v.2 with winxp pro sp3

Everything worked fine until a few days ago. After a Skype update(?) or a
Windows XP pro update(?) the microphone + headphone are recognized when inserted
in the front panel, the headphone works but the microphone configuration dialogs
behave as if the microphone is not existing. I have deinstalled and reinstalled
the audio drivers, no help. Seems to be a frequent problem but I can´t figure
out a solution to make the microphone work after several hours. Mike is ok,
works in other computer. What is the solution?
Thankful for any advice
Franz47