My biggest gripe is probably uncontrollable by N3V, and that is content creators who don't post a decent thumbnail of the listed asset. Many times, there are a group of assets in the thumbnail showing the different items the content creator made in a group. I like to see INDIVIDUAL screenshots of each particular item. Then there's the idiot who posts a thumbnail of the WORD the asset is, such as "TRUCK" or "SWITCH" or sometimes, even the content creator's username! Comon' folks, get with the program. The thumbnail pix are there for a reason, and that's to show the potential user what exactly he or she is contemplating downloading.
As for the page up/down keys, mine work just fine.