I'm not entirely sure what information I need to put here, but I've been trying to run the Linux client (as well as the web-client) under Ubuntu Linux version 11.04 with a Radeon HD 4350 graphics card with 512MB of memory.
(running the Steam client under Windows 7 Pro on the same hardware makes it perform flawlessly)
I've been getting a black window that closes as soon as the background music starts, which doesn't even give me any time to try entering my log-in credentials.
Does anyone have any suggestions as to what to look for or where to find the log files?
EDIT: Using the Protected Drivers program to remove the fglrx proprietary drivers and enabling Compatibility Mode for the graphics made everything work properly!
I understand there are several problems with ati graphics card, although I didn't find any with that specific model. Are you sure you have propetary drivers installed? If so, and they are updated, try installing previous versions. Log files are located in the installation folder, you should paste the contents of projectx.log.