In Registry Editor, locate the following registry key:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders
In the right pane, note the values in the Data field of each entry. If any value contains a drive that is not correct for your computer, right-click the entry, type c:\my documents in the Value data box, and then click OK.
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion
On the right hand side right-click and modify the value of "CommonFilesDir" to C:\Program Files\Common Files.
However if your My Documents is Mapped to something else you do not have to make changes this issue has been fixed in MR4MP2
You can directly install SEP even if your directory is mapped to some other computer or drive.