I tried to install the new ATI driver 8.4 on Ubuntu 8.04 64 bit in many different ways, but never works and gets stuck with a black screen, with no error message. (32 bit version works regularly)

System with 8 GB RAM
and ASUS 3850 512 MB

Nothing else is strange apart from these log lines:

kernel log: [fglrx] Maximum main memory to use for locked dma buffers: 7766 MBytes.
kernel log: [fglrx] ASYNCIO init succeed!
kernel log: [fglrx] PAT is enabled successfully!
kernel log: [fglrx] module loaded - fglrx 8.47.3 [Feb 25 2008] on minor 0

kernel log: mtrr: type mismatch for d0000000,10000000 old: write-back new: write-combining

daemon log: gdm[5828]: GLib-CRITICAL: g_key_file_get_string: assertion `key_file != NULL' failed
daemon log: gdm[5828]: GLib-CRITICAL: g_key_file_free: assertion `key_file != NULL' failed

any suggestions?