Onboard Sound Problems

I have encountered this annoying problem lately for the past month whereby my sound would "hang" after around 8-10 hours usage of the computer. The sound would keep repeating and the only way to stop it is to reboot the computer. Is this due to heat issues? I have found that the problem occurs more often during the day as oppose to at night when my air-con is switched on. However i have monitored the temperatures within my computer with Everest and found nothing abnormal with the temperatures. I'm using onboard sound and have also updated my sound drivers to the latest ones. Anyone know if this is due to a software malfunction or hardware defect? Or anyone who have encountered similar problems and are able to help?

My rig specs are as follows:
Intel E6600 @ 2.4ghz
Gigabyte 965P-S3
MSI 8800GTS 320MB OC
Kingston 667 1gb x2
Western Digital 320gb
Samsung DVDRW 18x
Coolermaster Realpower 450w
Coolermaster Centurion 5
Windows Vista Home Premium
Creative SBS 580 5.1