Just got a Mac Mini and tried hooking it up to 65" Fujitsu. Used mini DVI - DVI adapter provided with mini to a DVI --> HDMI cable attached to a video switch. Switch is configured correctly. Audio is going thru my Rotel receiver via mini jack optical cable. I turned on the Mini and NO picture on TV. What could be wrong, and what can I do about it?
Any and all help most appreciated.

What happens when you don't complicate things by going through a switch and connect directly instead?

Haven't tried that, thought about it. I have a Sima switch, and it was configured by an installer who I had out to the house to add a RTI remote to my system. If I disconnect the switch, will it affect it when I reconnect it.
Just looked at the cables. I have a HDMI cable running behind the wall to the TV. My end of this HDMI cable is male. guess the initial installer did not plan for other HDMI sources being fed to the TV. So many years ago I bought the SIMA switch, which allowed me to feed the TV with a cable signal from my Sony DHG HDD250 DVR via HDMI. So now all I have are male HDMI ends, so as I see it, no way to get the male end of the mini DVI -DVI to HDMI cable to the TV HDMI cable which is also male.

The thing is, computers aren't like plug and play CE devices, they're more complex. Sometimes, what you're trying to do would "just work" with little trouble, often that depends on the display. But, basically, what most of us here would do before trying to send video through a switch or AVR is connect directly--see what you're up against, see what res options you're offered by OS X--then re-try by going through an intermediate device.

I'm not recommending you screw up your system, and have no idea what would happen if you disconnect things. You're speaking a language I don't understand, SIMA, installer, RTI, etc. So you have a difficult decision...what's the native res of the plasma?

TV says it will do 1360 x 768

you've got a lot of variables that might be causing trouble:

1) mini-DVI to DVI adapter

2) DVI to HDMI Cable

3) Switch

Have you tried connecting the DVI to HDMI cable directly to your TV (bypassing the switch)? That's the first thing I would try.