Windows 7 Boot Manager issue

When I turn on my PC it opens Windows Boot Manager and gives me 2 options:
1. Previous version of Windows
2. Windows 7.


*It also has a 'Tools' option, with 'Windows Memory Diagnostic', though running this tool does not help.



If I select option one I get an error message regarding " computer disk hardware configuration problem" and am told Windows "could not read from selected boot disk", and the computer restarts. Option 2 loads Windows 7 perfectly.



When I installed Windows 7 I did so over the top of XP, and accidentally had an external hard drive attached during installation which was formatted and installed with Windows. I wonder if my PC is looking for this hard drive.


I want to make changes so that Windows Boot Manager does not load at all. I am not interested in a dual-boot PC. Windows 7 is enough for me. I also noticed that there is a file on my C drive called 'Windows.old.' There are the usual 'Documents and Settings' and 'Program Files' folders located here, none of which I am interested in keeping.


My questions are these:


1. Why does Windows Boot Manager open when I turn on the computer or restart?
2. How do I stop it doing this?
3. If I delete the folder "Windows.old", will this cause me any problems?



Any suggestions would be appreciated.

I did this
"right click computer select properties

select advanced

under startup and recovery select settings

uncheck "time to display list of operating systems" or reduce the seconds to 0"

and this
"That's only hiding the problem. You need to remove the old dual boot OS entry using EasyBCD 2.0 "Edit Boot Menu" - highlight old OS, Delete, Save, Restart."

and problem is solved. Though there is an extra 10-15 second lag during start-up.