Fix for - Failed to install sed64: general error.
To resolve this:
Open Run then type sysdm.cpl .
Click Enter .
Go to Advanced tab.
Click Environment Variables button.
Under the System variables section, make sure that the variable TMP has a value of C:\WINDOWS\TEMP
Restart the computer.
Perform a Sophos update.
Open the file alc.log to confirm if all Sophos components have been installed.
32-bit: C:\Documents and Settings\All Users\Application Data\Sophos\AutoUpdate\Logs.
64-bit: C:\ProgramData\Sophos\AutoUpdate\Logs.