What Model PC? (and What Operating System?). Make sure it's not a meda player that is doing it. Close any and all media players and see if it stops.
Barring a defective drive (either the front panel open/close switch or an internal problem), it could be malware. Do a complete spyware scan with a program such as "MBAM" that has an up to date data file and also do a complete virus scan with up to date virus program and data file.
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Dell forum member since 2002
Dell Inspiron 15 - 5577 Laptop
Home Built Desktop PC with ASUS ROG Z170, i7 6700K CPU
Windows 10 64 bit Pro and Windows 10 Insider Program Beta Versions. SSD drives. Cakewalk by BandLab and Studio One 4.1 Recordng Studio Software.