I have just installed safeboot 5.1 on a Dell inspiron 2500 & now the initial Safeboot login screen is corrupted - looks like 4 minature versions of the safeboot screen with garbelled images around the screen - numlock etc still work!!
A weird coincidence...i've just come across this problem the day after you 🙂
I've got a Dell Inspiron 2600 with exactly the same problem. However, this problem only occured after i updated the BIOS (to A11) to try to resolve another Safeboot issue. Safeboot was OK on boot up until this point.
I'm going to try to revert to a previous BIOS, although i'm not even sure of this is possible. I'll post back if I can get any further...unfortunately this is the kind of thing where Dell will say speak to McAfee and McAfee will say speak to Dell!!