Hi Thomas - I had the same problem as you - error 161 after I had changed the battery. I reset the time, but still got the same error over and over. I finally fixed my laptop today. When I turned it on, I had the Esc key pressed, and I got errors 76 and 301 (keyboard errors) - but not error 161! I let my finger off the Esc key then, and the computer got to a "test" screen.
I clicked "test", but I didn't run any of the tests (I've run them thousands of times already) - instead I clicked Exit, and it took me to the bios "Easy Setup" screen. I went in to "Config", then to "Quick Boot", and set it to "Disable". Then I went in to "Initialize", and initialized the bios. Then, I clicked "Exit", and clicked "Restart".
Once I got the computer booted up (!), I tried to run Scandisk. That's when I found out I had a nasty malware running, called Websearch - it was firing off two programs, Wsup, and Wtoolsa - both of which you couldn't kill, because they'd start each other up again. I searched the web and found out what-all I needed to get rid of, both on the hard drive, and in the registry, and then I was able to kill those two processes.
I then shut off the screen saver (important), and closed all processes except Systray and Explorer, in the task manager. I ran scandisk, and then I defragged the hard drive. Then, with much trepidation, I shut down the computer.
When I rebooted, it came up with no problems, and I haven't seen the error 161 since! I don't know if it was removing the malware, or running scandisk and defragging, or setting "Quick Boot" to disabled - but now it works, so there's some stuff for you to try.
BTW, it did take a few tries for my "Esc" key trick to work - keep at it!
Wendy, January 2006