IPod 3G troubles; top bar disappears?

I have an iPod touch 3G and I'm having a problem with it. The top bar sometimes just disappears. (The bar with the time, wi-fi connection, battery power etc. on it at the top) My iPod is jailbroken but I haven't had this problem until recently. Sometimes the bar will reappear if I go to turn it off, and then cancel. But I was wondering if there is something that is causing this or if it's just a glitch of 3G iPod touches. Thanks for any answers(: