This has nothing to do with hijack. The seek tool itself is dodgy and occasionally slips into a mode where it doesn't update the graph. I have no idea why it goes away, and I have no idea what makes it come back, but I've seen this as well.

As for why you're not getting a hijack menu, you said you "reinstalled the beta 7"... Do you mean you re-did the beta7 upgrade? If you do that, it erases the Hiajck kernel and replaces it with a stock beta7 kernel. You have to do the beta7 upgrade first, THEN flash the Hijack kernel.

If you already did that, then I have no idea why you're losing your hijack menu.