I have not seen the issue you outlined (I also use the SD menus). I seem to remember other people complaining so I do not think you are alone. Hopefully it is a bug being fixed.
You could try doing planned weekly soft restarts/reboots and see if that prevents the problem. A Premiere takes about 8 minutes to restart so you need to do it at some point where you do not want to use it for at least 8 minutes and it isn't scheduled to record anything. I reboot my TiVos now and then because it seems to clean up performance issues.
Good Luck,
You could try doing planned weekly soft restarts/reboots and see if that prevents the problem. A Premiere takes about 8 minutes to restart so you need to do it at some point where you do not want to use it for at least 8 minutes and it isn't scheduled to record anything. I reboot my TiVos now and then because it seems to clean up performance issues.
Good Luck,