Safe mode works...that means the hard drive is okay, the video card and screen are okay.
Quite possibly a driver problem.
Divide-and-conquer should work: do a selective boot (using msconfig) and keep enabling program by program,...
Run Dell's diagnostics on the HDD--make sure the program says it's okay.
If you still have doubts, have a Dell tech look at it.
If a cpu fails, that sucks. Just get a new cpu.
If a fan fails, that sucks. Just get a new fan.
If a video...