This has started to happen to me as well.
As I'm typing this, in Safari, the application will suddenly jump to the Finder and the rest of the senten
Did you see what happened there? It doesn't matter which application I'm in, it will suddenly go to the back and the Finder will become the highlihted window.
I'm using a Powerbook G4 1.67GHz with 512 MB DDR2 SDRAM. The problem arises even if there is only one application open. The problem is probably due to my own attempts to solve other issues. At work I was blocked out of the network and a message said that my powerbook was making potentially harmful requests; possibly due to a virus or trojan.
Trying to figure out what was going on, I remembered that I'd been getting a strange message on preferences/network settings. It said
"Your network settings have been changed by another application" and would not let me change the settings or even close down preferences. I found a fix for this at
http://discussions.apple.com/thread.jspa?threadID=1710040&tstart=0
where I found the following advice:
"Go to Library/Preferences/SystemConfiguration and delete the following (suggest make copies to the desktop first if in doubt):
com.apple.airport.preferences.plist
NetworkInterfaces.plist
preferences.plist
com.apple.nat.plist"
I deleted the files and it did indeed get rid of the annoying message that my network preferences had been changed by another application. However, since then, I've been getting the application switching problem.
I store all my documents on dotmac and I have an external hard drive with all my music and photos etc so I'm very tempted to just reinstall MacOSx from scratch.
Any suggestions?