I also got Ubuntu Dapper (alfa or beta version) system freeze when changed display resolution on computer with ATI Radeon R3xx or RV3xx video card. It seems bug #29354 and bug #50504 are related to this bug, maybe this bug is duplicate ?
-- Switching resolution hangs computer on (9600 mobility) https://launchpad.net/bugs/28171 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs