I have a two-month old swivel screen iMac. A few days ago, after I would wake the computer up from sleep, the screen would be white and nothing I did could bring it back to the normal screen. If I swiveled the screen or hit it, sometimes multi-colored horizontal or vertical lines would appear. What's wrong with my beloved iMac?

Sounds like a bad connection in the screen somewhere. See if an Apple dealer can take a look at it and diagnose anything.

p

Sound like you have a defective Analog Video Board. You will probably have to repalce it.
Before that, please try this:
reset pram (restart, while pressing apple-option-P-R; wait for the chime (3 times)
reset fimrware (restart, press apple-option-O-F; type 'reset-nvram, set-defaults, reset-all
try a cuda reset (on the motherboard there will be a small switch, tunr the mac off, pull the power plug out, turn it on (..), press the small swtich for about 45-50 seconds. After that it should start up.
If this doenst d othe trick, most likely you will have to replace the AVB (about 300-400 euro (340 usd)...

good luck

jp

Unless I'm missing something terribly obscure, the new iMacs don't have any analogue video components at all, because LCDs are entirely digital.

p