If you are receiving internet radio, your audio must be working again. Your first post said that it wasn't functioning. What did you do just before it started again? Have you tried using the same media player to play music stored on the N800 or on a data card? Were you using the built-in Media Player or some other?

The thing that really puzzles me is that I have the opposite experience with the built-in Media Player. It is the most likely app to cause a freeze-up of my N800. Usually this happens when I try to select a menu item before the app is ready, such as when it is refreshing the menu. Have you tried slowing yourself down? (Pause briefly before making your next stab at the screen.)

The Images app is another one that sometimes freezes on me. It happens when I try to load or edit pictures faster than the N800 can handle. The Nokia 770 is much worse in this way - significantly, its processor is slower and less powerful than the N800's. It sounds to me as if you might be expecting your N800 to work faster than it is capable of doing. You might also have an overcrowded root file system (rootfs).

Do you have a lot of apps installed? Do you tend to open several at a time? Are you booting from the internal flash or from a media card partition? How much swap space do you have available? (Swap is also called virtual memory.) All of these could make a difference. So:

remove apps that you don't need;

activate more virtual memory, or create a large swap partition on one of your media cards;

limit yourself to having three or four windows open at a time;

and slow down a bit.

Depending on how you installed apps in the first place, the associated .deb files could be taking up a lot of space somewhere in the /var directory, even after you have uninstalled the apps. You could find out more about this by searching the forum.

Like you, I can usually close the offending app and regain responsiveness after pressing the power switch. I move up and down the resulting menu a couple of times, using the navigation button, and then select "Cancel". That usually does the trick. I don't have to do this very often, since learning to avoid the habits that make the device freeze.

If you haven't set up a bootable rootfs on a media card, that is something that can improve performance tremendously. If you search on "MMC boot", "SD boot" or "bootmenu", you should be able to find information about this. Bunanson has written some extremely helpful step-by-step guides.

I hope that some of this will help.