I assume you are probably talking about the Windows native audio services, so....
into the search or run dialog box and hit enter.
Scoll as needed and find
Multimedia Class Scheduler
Windows Audio Endpoint Builder
Double click them and make sure their respective "Startup Type" is set to Automatic
Additonally you may want to search the event viewer to see if there are any error logs being reported pertaining to audio. Expand Windows Logs, check application and system. A quick and dirty right click and find "audio" might get you started. Perhaps a third party audio service from another vendor might be conflicting.
I would think if it takes two boots to get the audio to work it is not recognizing the driver on the first attempt. If the other suggestions are not the fix, maybe check the Device Manager to see what you show for sound. You may have one or more sound devices, but at least one should probably be an HD Audio and they should not have any yellow marks.
On my system, I load the Realtek drivers which also have their own control panel. If yours is not working correctly, you might want to check your manufacturer to see if any Windows 7 drivers are available.