Well my setup (notebook) is:

*-cpu                                                                                                                                       
          product: Intel(R) Pentium(R) M processor 2.13GHz

*-memory                                                                                                                                    
          physical id: 81                                                                                                                        
          slot: System board or motherboard                                                                                                      
          size: 2GiB                                                                                                                             
          capacity: 2GiB                                                                                                                         
        *-bank:0                                                                                                                                 
             description: SODIMM SDRAM Synchronous                                                                                               
             physical id: 0                                                                                                                      
             slot: DIMM 0                                                                                                                        
             size: 1GiB                                                                                                                          
             width: 64 bits                                                                                                                      
        *-bank:1                                                                                                                                 
             description: SODIMM SDRAM Synchronous                                                                                               
             physical id: 1                                                                                                                      
             slot: DIMM 1                                                                                                                        
             size: 1GiB                                                                                                                          
             width: 64 bits        

I.e. two completely identical RAM sticks (2x1GB) from Corsair brand (2 packages with same part number), so there is no chance this error to have anything to do with my memory - it works flawless. It will be ridiculous Canonical to blame user's hardware(memory) for this pretty clear to me bug ;)

Of course I could that weired workaround, but this will just prove to me that there is a bug (some memory management issue).

Yesterday I had some time, so I've installed Kubuntu 8.10 first and then upgraded to 9.04 via update-notifier-kde.

I hope Canonical will pay attention and fix the installer :) I'm pretty often use this method to install from scratch than upgrading current OS (old habit from M$ Win) :)