When an STOP 7B occurs after installing Service Pack 1 for Windows 7 on an external hard disk this problem might be caused by the existence of UpperFilters TsUsbFlt in the Windows registry in the SYSTEM-hive. Remove the value tsusbflt in the UpperFilters in all ControlSet of the following registry-key HKEY_LOCAL_MACHINE\SYSTEM\ControlSetnnn\CLASS\{36FC9e60-c465-11cf-8056-44553540000} nnn is a three-digit number Recover from STOP 7B from the Windows-installation on an USB disk. Press F8 immediately after booting from the external hard disk and before the Windows logo appears. You should press the F8-key a long time. On the black screen with the title Advanced Boot Options select the first option “Repair your Computer” and press the Enter-key. When the window System Recovery Options appears select your language and keyboard. On the second window System Recovery Options select the first radio button before “Use recovery tools …” and click on the Next>-button. From the list of recovery tools select the last one “Command Prompt” A command-prompt window appears. Be sure that you are Administrator. Find out which drive letter refers to the external hard disk. In my example this is G: Make a copy of file SYSTEM in the folder “\WINDOWS\SYSTEM32\CONFIG” on the external hard disk (e.g. G: ). This is a backup. Type regedit.exe in the command-window In window "Registry Editor" select in the left pane HKEY_LOCAL_MACHINE Click in the menu-bar on “File” and within “File” on “Load Hive…” In window “Load Hive” type after “File name:” G:\WINDOWS\SYSTEM\CONFIG and press the Enter-key. The file content of the window changes. Select “SYSTEM” and press the Enter-key. Tiny window “Load Hive” appears with an input field with heading “Key name”. Type a name e.g. tmp, and press the OK-button. Don’t use key name SYSTEM or SOFTWARE. In window “Registry Editor” expand in the left pane HKEY_LOCAL_MACHINE” and within that key expand key “tmp” (or the name you typed before) Expand the first key with the name ControlSetnnn (where nnn is a three-digit number) and expand “Control” and within “Control” expand “Class”. Select “{36FC9e60-c465-11cf-8056-44553540000}" within "Class" In the right pane of the windows you should see Class REG_SZ USB. Look for Name UpperFilters in the right pane. If it is found look for the value TsUsbFlt. If the value is shown doubleclick on UpperFilters and remove the value tsusbflt. Press the OK-button. Repeat step 15 to 17 for all ControlSetnnn in the left pane of the window in branch “tmp”. Select key “tmp” (or the name you typed before) in the left pane of the window. Select in the menu-bar “File” and within “File” Unload Hive…” Click on the Yes-button on the Confirm Unload Hive-prompt. Close the window “Registry Editor”. Restart the system and boot normally from the external hard disk. The configuration of Service Pack 1 should now continue.