Can anyone help me understand why sometimes (usually when I've been practicing for a relatively long time) Skritter starts giving me words/characters that aren't due yet, even when there are plenty of new words in the queue it could give me instead? How do I persuade it not to make me review things I don't need to, but instead to give me new words?

That's generally because it's running into server trouble. Look in your Javascript error console (instructions vary depending on your web browser) and you'll probably see the dreaded "Error 500". Also check the lag indicator (a little rectangle on the bottom right).

James

When I encounter such oddities often it helps to go back out to the main practice page (click on "study") and then back to whatever list or "everything" that I had been working on. Maybe it's just in my head but I think that things get reset. This is certainly a way to fix a "number of items to review" that's gone haywire.

@sarac - that does seem to help, but I'm finding that at best I might get one or two new words before I get stuck again. @jww1066, you're right - it does seem to correlate with errors that show up in the Javascript console. I don't know enough about Javascript to decode them, though. I'm using Skritter in Chrome running on Vista. I'm in the US, on wi-fi with cable broadband and not encountering discernible errors on other sites. I am encountering problems in both the alpha version of Skritter and the regular version, but more with the alpha version.

Dorritg, can you install the debug version of Flash player for me? This might help figure out if there are any unknown errors going on.
http://www.adobe.com/support/flashplayer/downloads.html

It's the "Plugin content debugger (for Netscape-compatible browsers)" link.