[SOLVED] something is messing with my hard disk setting

[ahmednashat23]

firs of all I have wd blue hard disk windows 7 ,gigabyte b85 ,intel cpu ,and every time I try to install new windows it says that I should vonvert to hard disk to gpt but I didnt change it!!! it happens every single time ,at my last try to install new windows I enconterd the same issue ,had to delete all partitions very annoying, but new thing happened this time my bios setting changed ,sata configuration changed to ahci in some magic way and I spent a week looking for solution to install my windows and get my pc working again at the end I realised that it was bios setting issue I wanna know what could be the cause of getting my setting magically changed like that

 

[SkyNetRising]

If you performed bios update, then this may change bios settings.
Also if BIOS battery has died, this also would reset BIOS settings.