Text and icons suddenly shrink on desktop and in browser windows

Something similar is happening to me in Firefox (I keep forgetting to use another browser to see if it's just Firefox), but I don't have to restart, I can just do command-plus or command-minus to undo. But it is driving me nutty, too. I can't seem to replicate it by touching the pad or moving my finger around in it, it just does it whenever -- but frequently, like several times in an hour of surfing. This never happened with my old iBook.

It doesn't happen in other programs, so it appears to be a nutty browser or nutty Mac+browser issue. It's not related to a certain website/s, as it happens w/ all of them.

I am having the same problem on a MacBook running OS 10.6.4. Just the icons on my desktop (not on my dock) suddenly shrink to 16 x 16. I go into View Options to make the icons larger again, then they suddenly shrink again! What is causing this?!

Ok i found an answer from another forum...

"Might happen if you've got "Pinch Open and Close" enabled in System Preferences -> Trackpad

To switch back make sure that top menu reads "Finder" -> View -> Show view options
Now enlarge the size of your desktop icons"

Is your screen resolution changing? Go to System Preferences > Displays, and take a note of the selected resolution before and after the change.

I'm having the same problem...I'll set the desktop icon size in Finder>View>Show View Options to 52x52 and then closing Safari automatically shrinks my HD icon to 16x16. Annoying.

Resolution stays the same--1280x800.