For Premiere 2 you need to make the stills the same size as the project if you have not done this. 225 Stills are a awfull lot to load especially if the are full resolution.
If you did make the stills the same size and still having trouble burning dvd make a dv-avi first, import this into a new seqence and burn to this sequence to dvd.
The backslash key for me has alway been zoom to sequence.