I have started having this problem recently, so it might be related to the IMG 1.7.1 update.
Say that I'm using the Search function in VOD to find episodes of NCIS. It might list 10 or so episodes (both SD and HD). But I can only scroll halfway down the list, and then it stops. It isn't frozen or anything, because I can still scroll back up. It just won't let me select any of the episodes that are more than halfway down the list.
I posted this reply to your comment over in the At Home blog:
Don't know if this helps or not......
I don't think it is a general problem with 1.7.1. I just did a search on NCIS, found 16 entries, both HD and SD, and was able to scroll down to them all, scoll back up, and select any entry I wanted, top or bottom of the list or anywhere in between.
Maybe it is specific to the type of STB you have? I used a QIP6416 DVR for my test. You might try pulling the power on the STB for a little while and plugging it back in, maybe that will fix it (it seems like briefly removing the power from the Verizon boxes will fix any number of "temporary" problems.....)