Dell inspiron 1525 down arrow key wont work

[DrFil]

Recently purchased non functioning Dell Inspiron 1525. Message was needed new m/b. When started would run for a few seconds only then crash. Checked RAM, HDD and peripherals all OK. Replaced m/b, formatted HDD and reloaded OS (Vista) after reinstalling Mediadirect 3.5. Starts and runs perfectly but the down arrow key wont work! Have tried all the suggestions on forums etc., No go. The keyboard works perfectly on another 1525 I have restored. Any ideas?

 

[mmaatt747]

Do other keyboards connected to your computer also have the same problem?

 

[DrFil]

Yes, I have tried 2 other 1525 keyboards and in neither did the down arrow work. One of these keyboards came from another functioning 1525 where the down arrow key works fine. I should also say that I tried an ext USB keyboard and it worked perfectly. So, I'm thinking it's the 'new' m/b.