Won't display all media

[Jam]

I am having problems that it won't always display all media items. I occasionally just get a speaker looking thing with a circle and a line through it. When thus happens it won't let me scroll or do nothing. In order to even scroll up or down on my phone I have to touch above or below the section stated.
I have an iphone4 4.0.1 and it's Jailbroken.
Thanks in advance.