I installed the matrix theme from the application catalog 2006, and it thoroughly messed up my interface after deinstalling it. BTW I had to deinstall it, since it had a black background for about anything, including anything black (such as the maemo-mapper unused sat signal strength bars).

Now the top right icons have moved to the left, the window controls (close, minimise) have moved _down_ - less screen real estate when not maximised! - and last but not least, my keyboard has its keys gone missing - I'm typing this on my pc, will upload a screeny from the n770 shortly.
Oh yeah, not even the thumb keyboard is working - it just doesn't pop up anymore....

I can type blind, but stylus blind typing is a bit of a stretch.

I tried to put things in order using lcars - and it works, but uninstalling that one brought me back to the mess the Matrix theme left behind... and I don't want lcars!

Does anyone know of a remedy?

Was that the selected theme when you uninstalled? Are you able to change to another theme?

I just managed to change to different colour and 14pt theme, this has fixed some of the issues, namely the scrollbar on the side is visible again; the only issue left over is that my right-hand top icons/status indicators are still on the left top (where normally the 'home' menu or app name text is), and the appname and such are still below all that - meaning I still didn't get back all of my screen real estate....

??
Another in a long series of reboots did it! Don't know why now it's suddenly okay, but anyway, I'm happy!

I have found that messing with themes is perhaps the most surefire way to cause a sudden need to reflash your device. I have also found several themes that induce the dreaded random reboot syndrome.