Both macs messed up after software "update"!

Hi. I "updated" the software on both my iMac and my PowerBook G4 last week.
Now every 30 seconds or so, the PowerBook switches to the Finder.
But that's not the worst of it.
The iMac was okay for a day or so after the software (and firmware) update --not upgrade-- but then it sort of froze. I restarted it several times and even switched users from the startup screen. Luckily, it froze with Internet Sharing on, so I am getting online with my laptop, which still works despite it's annoying Finder-blip.
Here is what is weird/going on with my iMac. I cannot open any files or folders on the desktop, or use the dock or the toolbar. I would blame it on the mouse except the Hot Corners still work (screensaver, lol.) I put it to sleep with the keyboard.

Perhaps I should mention that these are both 2006 models, and this is the first time I've had trouble with them. No apple stores closer than 7 hours away... Thank you anybody who can help.

When you say updated the software OS or third party?
Did said update have a minimum system requirement ?

thank you, osxx, I wish I could remember. It was about 5 days ago for both of them. I am pretty sure they did have mimimun system requirements, maybe 80 MB? I can tell you on the PowerBook it updated Safari to 3.0.4. The iMac updated the Firmware, Safari, and Java I believe.

What version of OSX is installed on the Powerbook and the iMac?

10.4.11 on the G4 and 10.4.7 on the iMac.

Btw, I have the original Installation disks for the iMac, if that makes any difference. I have recently backed up my files, so if I have to do a clean install or whatever I guess that'd be okay. I have a feeling, though, it's something very simple.
I could not find anything addressing either problem (iMac or PBG4) in The Missing Manual, but perhaps it is something I have overlooked.
My real fear is that the iMac will wake from sleep and no longer be Sharing the Internet. I've had to reStart Sharing now and again. If that happens I will be offline until the iMac problem is solved. Again, everybody, thank you for your help.
Sorry if I am overposting--brevity was never my strong suit.

No software updates for Tiger for some time now, so it was not an Apple update. There was an Airport update a week or so ago but cannot recall if it was for Tiger.

Yes. I strongly dislike performing software "updates," so I put it off as long as possible (until the Update alerts get on my nerves, the computer seems to be running slow, etc.).

The one I just did on the PowerBook G4 updated Safari to 3.0.4. I'm sure it was months old. Should I look for a newer one? I think I saw Safari 5.? Would that even work on an old PowerBook. I thought of trying that. That would not fix the iMac though, since it is frozen.


A side story re install disks: I took the powerbook to an apple store in madison, wisconsin for help getting online. It was in the original box: I felt like I was carrying a briefcase of gold, like it should have been chained to my wrist, and all eyes were on me! Oh, how the Geniuses moaned and looked at it longingly... Anyway, I think one of them stole the OSX Install disk! Right out of the box! When I looked later, only the Application disk was there. I called apple--appleCare, I think-- and they said they'd send me the disk but it never came.

I have satellite internet. If iMac quits Sharing, I can plug in the PowerBook, so I won't be internet-less.
Both problems are still in effect.
Thank you, I will look into the Four Mac Fox-thingy.

I don't get it. Am I going to have to buy a new computer? My iMac is still stuck. I am going to call computer shops in town today. Hoping one of them does macs.

OKAY!!! Called TheMacMan (themacman.net) in Paonia, CO. and he was able to help me. Guess what it was. Not a "failing harddrive" like 3 places said, not a need to reInstall from the original disks like 2 other places suggested. . . It was the mouse batteries, folks!

If anyone else out there is still stumped, I highly recommend calling this guy first. 970-963-MACS (907-963-6227)