Whenever I start my computer, My Documents/My Computer opens automatically at windows startup.

Sol: Open regedit and goto:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon

In right-side pane, change value of "Userinit" to:

C:\WINDOWS\system32\userinit.exe,

NOTE: If you have windows installed in other drives, then change C:\ to that drive label.

Now goto:

HKEY_CURRENT_USER\Software\Microsoft\Windows\Current Version\Explorer\Advanced

In right-side pane, change value of "PersistBrowsers" to 0

Now log off windows and it should solve the problem.