Help me i have problem with microphone

I am new to this forum however i have a very advanced knowledge of windows operating systems. I recently was having problems with my speech recognition engine, however I fixed it as it was the result of winuntilities cleaning the registry entries needed for speech recognition to run. However another problem has arisen and i am not sure where it is coming from occasionally my microphone will stop picking up. my external mic works fine when i plug it in (its a usb mic, it loads a slightly different driver) however my internal mic will stop working after about 24 hours. I have checked all my cleaning programs and it does not appear to affect anything associated to my sigmatel mic. I have a Dell Inspiron 600m. I have done a decent job in cleaning out my system using ccleaner, winutilities, disc clean up, and tune up utilities 2010. I have been able to restore functionality of the mic by reinstalling the driver again, but i am more curious about what is causing it to fail. I believe that it may be another program stealing its control but i am not sure. I believe that my computer is completely virus free as i have avast for my antivirus from the beginning, and I have zone alarm as my firewall. I have reason to believe this is adequate enough software to protect my investment.
I have installed revo uninstaller so if there is a program that i no longer desire it should wipe my disc almost 100% clean.