Hello I have a Toshiba S55-A model laptop (don't know the exact model) and it freezes on startup. When I turn it on normally, it shows me only my cursor, no task bar or anything, and I can move it around a little before it just freezes. When this happens the vents start to get really hot as well.
In safe mode it runs normally and it's also running off a fresh Windows 8 installation so there aren't any non Windows startup services or programs.
If it runs fine in "Safe Mode" but outside it, then it is a software issue. Were it hardware it would still give you trouble in "Safe Mode". Unless you are trying to use the GPU rather than the integrated graphics. Try running it that way and see if the problem goes away. If it does, Either the GPU is overheating or going bad.