Zapping the pram didn't help me either. And guess what. I also have a ViewSonic. Model PT775.

Yossie, what Mac do you have? And what video card are you using?

System Pref Displays just showed VGA. After zapping the pram, it continued to show VGA. No change in resolution choices after zapping the pram.

The only change was that iTunes attempted to use 70Hz instead of 60Hz. 70Hz is not on my resolution list either (neither recommended nor unrecommended). 75Hz is on my list, but not 70Hz.

I think that's the problem. For whatever reason, iTunes is attempting to set our monitors at a resolution in which our monitors cannot use (as limited by our video cards). Maybe iTunes is supposed to be reading something from our monitors/video cards to find out what resolutions we can display, and on certain monitors/video cards, it reads it incorrectly?

I'm just guessing, of course. But it seems odd that I could view full screen visuals with my old video card, and then lose that ability when I install a new video card. And, yet, other people have the exact same symptoms simply by upgrading to iTunes 3.0 (as reported on the Apple boards and other boards). So there has to be some connection with the way iTunes is trying to determine which resolutions are monitors/video cards are capable of displaying, and when it gets it wrong, the result is no full screen visuals.

If that is correct, then this could be fixed in future upgrades for iTunes.

Display card and video card..
 

The monitor, as stated, is a View Sonic 21" PT813 (professional series) (from various web sites):
Input Signal
Video Signal : Analog
H Frequency : 30-107 Khz
V Frequency : 50-160 Hz
Sync Signal : Separate, Composite, Green
Power Mac (from 640 x 480 to 1600 x 1200)

The display card is the one the Mac came with:
Display card
Card type: display
Card name: ATY,Rage128Ps
Card model: ATY,Rage128Pro
Card ROM #: 113-63001-108
Card revision: 0
Card vendor ID: 1002
VRAM size: 16 MB
Should be OK, no? I am guessing that you are right, btw.

My Macs:
128K Original Mac
Mac SE 30
Mac IIci
PowerMac 7500
PowerMac G4 350Mhz

- Yossie

ViewSonic Professional Series here too. PT775. Specs here.

Input Signal
Video Signal : Analog
H Frequency : 30-96 Khz
V Frequency : 50-160 Hz
Sync Signal : Separate, Composite, Green

Maximum Resolution
Maximum : Up to 1600x1200, 77 Hz
Macintosh : 1280x1024, 75Hz
Flicker free : 1280x1024, 89 Hz

Display card
Card type: display
Card name: ATY,mach64_3DU
Card model: ATY,GT-B
Card ROM #: 113-XXXXX-1.1 (yes, it really has all those X's in there)
Card revision: 154
Card vendor ID: 1002
VRAM size: 32 MB

Affected Mac: Beige G3 Server.

Interesting coincidence that we both have professional series ViewSonic monitors.

I have a flat panel iMac.

I'm afraid to say that it works fine for me, just in case it breaks after I say that. ;)

I have the same symptoms with my WallStreet PowerBook, which no longer gives me ANY display resolutions other than 1024 x 768.

I used to have other resolutions if I unchecked "show resolutions recommended", AND I used to be able to set iTunes to full screen display.