This sounds as if the image window is off-screen. Have you disconnected a second monitor, or changed desktop resolution, or tweaked some other display setting?
Make sure you have installed the patch for CS5 from here: http://www.adobe.com/support/downloads/detail.jsp?ftpID=4733
And update your video drivers from the card manufacturer's web site.
The 64 bit version of CS5 works just fine.
If it is not working fine, then you have a video driver problem. For your nVidia card, visit this site to check for updated drivers:
Answer to Noel Carboni:
Thanks for your suggestion. I installed the most recent driver, but it did not help.
If I open a psd file the background is empty unless I set the zoom scale to 25%. For any other zoom ratio I get an iakiramemashitamage only as long as a move the file with mouse. If I stop and deppress the mouse button it disappears. Never seen such strange behavior. The 32 bit version works normally.
akiramemashita (japanese)= I've given up.