The SQLite library used in Firefox 4 is newer than the one that was around at the time Window Washer was last updated. Webroot will be updating Window Washer with a new version that supports Firefox 4 and also may have a patch for the current version until then.

To fix it sooner, you can download the new SQLite3.dll from the SQLite web site and place it in the Window Washer folder, overwriting the current one. The Window Washer service and the tray icon both must be shut down to replace this file.

Doesn't work, at least not for me. I even went in to Window Washer (after following your instructions) and told it not to clean anything to do with Firefox, but still nothing. When I try to run a wash it just sits there, looking at me......like H.A.L.