It is not malware. I did some digging and it is related to AMD TrueAudio. See here for information: AMD TrueAudio Technology and here but it is in German: Frage zu Windows Dienst "acp user service"- Was ist das ? - ComputerBase Forum and here a video : EXCLUSIVE: Lichdom Demo featuring AMD TrueAudio - YouTube This technology is included in the AMD R7 and R9 series of graphics cards. ACP stands for Audio co-processor.
Could this have something to do with a weird sound problem I have every time my computer comes out of sleep mode/hibernation?
Whenever I resume operations from either sleep or hibernation, the sound has a very pronounced scratchy sound, like a very dirty old vinyl record. It makes it impossible to watch a movie since none of the words can be understood, and all sound is distorted horribly.
This problem is fixed when I open the sound control panel, select the speakers, and do something, like enable/disable the audio enhancements. At that point any games I was playing stop producing sound until I restart them, but the sound is fine and normal once again. A reboot also fixes the problem, but it is easier to 'reset' the sound driver by disabling and then re-enabling the audio enhancements.