I just had a quick browse-through of Power DVD 10 Ultra MkII help and I don't find the page-up/page-down keys mentioned as hot-keys for any function. Are you sure of what you know?
I went through this too. Nowhere Page-up/Page Down.
EDIT: I played a DVD and tried the Page-up/Page-down keys. The Page-down key advances the video by 6 seconds. The Page-up key rolls the video back by 5 seconds. Again .
May be you can uninstall it completely using Revo Uninstaller, reinstall afresh and check if you can't live without it.
And if by chance you are using the Page-up/Page-down keys in the Numerical keypad (9/3) you have to disengage the Num Lock (Num Lock off).
Neither the page up/page down keys in the keypad nor the ones in the top row of keys, next to the Home keys work. I have Cyberlink PowerDVD 10.0.1705.51. The Page Up/Page Down button thing is in the Advanced section under the keyboard mouse options. When I press either set of keys, nothing happens except the picture "jiggles" but doesn't go forward or back or stop. I saw the Prior/Next thing, but my keyboard doesn't have those buttons.
The version in which I checked is 10.0.2701.51.(MarkII Ultra version.) Just two days back I updated it from build 2429. It is part of the Cyberlink Media Suite 9 Ultra. As I had stated Pageup key rolls back and Pagedown key advances. Amusing.
I am afraid only someone who has the exact version as yours can tell whether it works for them and confirm whether you have a problem if at all.
1705 seems quite old.Have you checked for updates? Usually there is one for the retail version and one for the OEM version (bundled with hardware). Try and get the appropriate update and then check it up.
I didn't pay for it, so I guess I'll just have to deal with it. The Page up/Page Down wouldn't work on one dvd, but it worked just fine on the next dvd I played.