Mic not working with Realtek HD

I have a dell Vostro 200 running Windows XP SP3 with a Realtek HD sound card. I am unable to get my mic working although it has previously worked on this computer.
The mic is part of a headset which I have checked on another computer and is working fine. The sound comes through perfectly clearly.
I have tried both front and back ports, the pink ports are correct according to graphics in Realtek Audio Manager.
I have tried almost every mixer setting I could think of including having everything unmuted and volume turned up to max.
I have been testing using Sound Recorder, Movie Maker, and Skype but dosen't seem to make any difference.
I have downloaded and installed latest driver over top of old one.
Realtek got me to send them a dump of sound card but have not got back to me.
Anyone have any ideas or suggestions?
 
You may have a driver conflict or a virus or other malware infection. Do you see any yellow exclamation points in the device manager?
 
Problem Resolved

Thanks for your reply
It turned out that the problem wasn't with the sound card but rather a hardware problem with the connections on the inside of the mic socket on the front of my computer. I purchased a new mic that worked on the front for a while but stopped but it works fine when plugged into back.
 
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