HI,
Have you moved iChat ?
Either out of the Applications Folder or creating a sub folder, say, for IM apps and putting it in there ?
Are there any Messages about it in Console ?
Are there Crash Logs?
In Console open up the Reveal Triangles to see ~/Library/Logs and look in Crash Reporter
Alternatively navigate to your Home Folder/Library/Logs/CrashReporter and double click the file to open in Console (it will open a separate window this way)
iChat is made up of four bits in Snow Leopard, the App, and 3 support bit called Frameworks tucked away in the System side of things.
If iChat is moved the path to the support Folders is different.
Hopefully any Console Log or Crash Report may help us.
Can you go to the app and do a get Info (CMD and I key together)
In the Panel that Opens what version does iChat say it is ?
At 10.6.8 iChat should be at version 5.0.3
10:03 PM Tuesday; June 28, 2011
Please, if posting Logs, do not post any Log info after the line "Binary Images for iChat"
G4/1GhzDual MDD (Leopard 10.5.8)
MacBookPro 2Gb( 10.6.8)
Mac OS X (10.6.7),
"Limit the Logs to the Bits above Binary Images." No, Seriously