Lenovo Y410; No sound from speakers. Help!

I will make this short and sweet. I have a lenovo Y410 with XP Pro SP3. It has worked fine for the past year and then about a month ago the on board speakers stopped emitting sound. I can still plug in headphones or external speakers and get sound though so I know the sound card is working. I tried reinstalling the driver many times and tweaking all the settings in Windows and the Realtek Sound managers. I cannot be sure but it seems like the speakers stop working after a Windows Security update. I have tried to restore my system to an earlier date using Windows Restore, but that too does not work anymore. I thought that the speakers themselves might actually be defective, but I can rule that out because I also have Ubuntu installed on this system and the on board speakers work fine in Ubuntu.

So there's my problem. I know my speakers work and the driver and sound card also work, but I still can't get any sound from my speakers. How weird is that? Any suggestions? Thanks for the help.