Your question is being answer in your other thread as I remember. Some has asked for further information so that they can help you.
The usual information that is require to troubleshoot you issue includes:
a. Do you have QuickTime installed on your computer with Premiere Elements 10? Have you said what computer operating system is involved?
b. Are you running Premiere Elements 10 as Run As Administrator and/or from a User Account with Administrative Privileges?
c. Where are these .mov and .mp4 files coming from? The brand/model and your camera settings would be very helpful, especially if you cannot supply the properties of these files. That .mov or .mp4 are file extension that wrap the video and audio compression, so we need to know the video and audio compression as well as the frame size, frame rate, interlaced or progressive, pixel aspect ratio. You can get all that from a MediaInfo properties read out
d. What are you setting as the project preset for your project?
e. Is there no sound just for these two video types .mov and .mp4 or is there no sound within Premiere Elements for anything?
f. Have you gone into the Edit Menu/Preferences/Audio Hardware and click on the ASIO button to check out the ASIO setting to make sure of what is enabled?
Please review the above. We will be watching for your details.
I agree with ATR, and as the question was asked in your other thread, http://forums.adobe.com/thread/1301319?tstart=0, I will Lock this thread, and we can continue the troubleshooting in that other thread.
Please answer the questions asked in that other thread, so that the real troubleshooting can begin. I added your PrE version (10), to that thread. Is it safe to assume that your PsE version is also 10? If so, please include that confirmation, in your responses in the other thread.
Thanks, and good luck,