I know that on my 150 I occasionally have some wierd problems that won't go away and the tech's whimsical solution to the problem is that "every once in a while it just needs a good enema".
So wait till a period of low activity, pop off the cover, find the CBMOD card (main processor card with the PCMCIA cards in it) and just FLIP (notice I said FLIP) the reset switch and let the system reboot. DO NOT hold down the reset switch. Doing so will make your life suck - the system will lose all of its programming and revert back to German. If that happens hopefully you have a recent KDE backup on disk someplace - then you will have to enter a code sequence onto the phone hooked up to the first digital port of the system to reset it all back to english - and then use your laptop to re-upload all of the system programming. Not a fun task when you are under stress!
I would say on the average I have to reboot the system every couple months to make wierd things go away, but I have not had any issues since I upgraded the system software to release 3.0.