I've just upgraded 5 client PC's to SP4.0 and also updated the EPDM client to SP4.0.
The updates were done from a newly created image file.
The issue I have is that the files icons within windows explorer are all of the red type so you can't tell whether they are assemblies, parts or drawings.
Also if you right click a file & choose "open" a new session of solidworks is launched regardless of whether you may already have one open.
I managed to fix one PC by running the image update again & then clicking "Restore File Associations" within the solidworks/options/ File Explorer menu.
I'm not have as much luck with the other PC's.