Windows 7 Ultimate Fails to Start

On a number of occasions Windows fails to start; there is a dark screen and a blinking cursor when the message that Windows is starting should be displayed. When I look at the bios display I see that problem is the boot option is set to either the hard drive that has no operating system or the empty CD/ DVD drive. In one case the system was set to boot from my printer's hard drive which normally doesn't appear as a choice.

Presently the computer is working fine. I am curious to know if someone else has had this problem.
 
I have not changed the boot drive selection except to fix this problem. Any ideas?



OS Name Microsoft Windows 7 Ultimate
Version 6.1.7601 Service Pack 1 Build 7601
Other OS Description Not Available
OS Manufacturer Microsoft Corporation
System Name CHARLES- PC
System Manufacturer DELL Inc.
System Model Studio XPS 435T/9000
System Type x64-based PC
Processor Intel(R) Core(TM) i7 CPU 940 @ 2.93GHz, 2934 Mhz, 4 Core(s), 8 Logical Processor(s)
BIOS Version/Date DELL INC. A16, 3/19/2009
SMBIOS Version 2.5
Windows Directory C:\windows
System Directory C:\windows\system32
Boot Device \Device\HarddiskVolume3
Locale United States
Hardware Abstraction Layer Version = "6.1.7601.17514"
User Name Charles-PC\Charles
Time Zone Eastern Daylight Time
Installed Physical Memory (RAM) 12.0 GB
Total Physical Memory 12.0 GB
Available Physical Memory 9.16 GB
Total Virtual Memory 24.0 GB
Available Virtual Memory 20.7 GB
Page File Space 12.0 GB
Page File C:\pagefile.sys