Figured out an easy solution! Many people seem to be getting "stuck" at a black screen when loading applications, even applications like multiMAN. To remedy this issue (temporarily), boot into recovery mode and select the option to fix the file system. This will put everything back in order, that is, until it screws up again. Rinse, wash, repeat as the issue arises.
I hope this has been of help.
UPDATE: Also, I am using OFW 3.55 with KMEAW's 3.55 CFW on top of it. multiMAN 1.13 is what I'm using to play games. I am using a Slim 120GB model. Hopefully my "fix" will work for you until this issue is stamped out!