blank screen upon boot in 10.1.5

[JesusFreak]

My comuter is a beige G3 266 with 256 Ram. Everything went fine until I decided to upgrade to osX. No problem whatsoever with 10.1.2 but after the upgrade to 10.1.5 the screen goes blank. I restarted in verbose mode (command-V) and saw that everything (including services etc.) was started, but the moment that the finder has to appear, indeed everything goes blank again.. I had the same when trying to install jaguar... where I see the startup screen (grey with the beautifull apple in the mid) wich goes blank but I do hear the computer performing its task and I'm sure if I could have seen what happened the machine would have asked me in what language I would like to install OSX.
Could this be a hardware problem? I rebooted in OS9.2 and had no problems. I indeed removed all my peripherals, USB card, extra Ram and network... but the problem persists. Frankly, I'm getting sick and tired of this, but I do love Jaguar. Did anybody have the same problem or knows the solution to this. Thanks in advance.

 

[JesusFreak]

Just checked my system log (/var/log/system.log).

localhost mach_kernel: ATY,mach64_3DUPro: Not usable
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localhost WindowServer[276]: WindowServer error: No screen drivers were loaded.
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localhost /System/Library/CoreServices/loginwindow.app/loginwindow: (ipc/send) invalid destination port : initCGDisplayState: cannont map display interlocks.

localhost /System/Library/CoreServices/loginwindow.app/loginwindow: KCGErrorFailure : CGSNewConnection cqnnot connect to server

localhost WindowServer[280]: WindowServer error: No screen drivers were loaded.

I don't think that is normal... the systemlog before the update to 10.1.5 gives no errors whatsoever.