Hello, my acer aspire 7520 laptop have a big and weird problem.. This laptop does not detect dvd drive or audio. DVD drive is not in bios, device manager or own computer. And audio say: No sound device is not installed. Sound works briefly, but stopped working in 10 minutes. And i have tried of the dvd drive next: Upper and LowerFilters are removed. Drivers are installed. Windows XP has installed, Windows 7 has installed, Windows vista of the original has been returned to the factory settings. If anyone have a fix ideas tell me.