Hey @inked, sorry this is happening to you! :s

Since you truly aren't receiving PC when this happens, this sounds like it could be the session timeout bug. This can happen either when you stay on the page for too long (which is less than ideal for a game that requires a lot of time) or when your connection is interrupted. Komodo has tried to fix this in the past but it sounds like it's returning, which is a bummer. I'm sure he's got a list of issues to look into after the release of Pixpet Adventure, but I'll be sure to remind him about this one.

If this is happening to you often, what I can recommend is to use a Sudoku solver. Normally I wouldn't encourage the use of solvers, but since it sounds like the game is wasting a lot of your time and giving you nothing, I'd say it's fair to use one in this case.

And as others have implied, it's good to make a habit of checking your pixcoin log after playing Roodoku. I understand in this case you had 0 PC, but in the future when you have some PC it helps to check, just in case you get the display bug instead, where the game does award you PC but acts like it didn't.

Again, sorry this is happening to you, and I hope that my input has helped in some way.