This error can have a number of causes, namely the file system, is the SD card formatted FAT32, ( some cards come formatted FAT16 as standard), or having the SD card set up incorrectly, for haret you need to have all files in the andboot folder.
Provided haret starts correctly, which it is since you cannot reach the post-install stage unless it is booting the kernel, then the only part of the procedure that can go wrong is the installer.
The only things I can think of that would cause the installer not to start is either the card itself, or problems with the andboot folder and/or the files inside.
The only advice I can give at the moment is to calmly start haret, watch the scrolling text until you get the pause, and the 'press d-pad to start installer' text.
At that point if you press the d-pad centre button, and hold it you will see '^@' on the screen, if you do not see the '^@' or see anything else then the installer cannot start, it will only respond to the correct key.
If you see anything else it is possible you have incorrectly set an option in default.txt file.
If all this still fails, then report back with anything you find, I may have some other ideas based on what you find out
XDA IIi ROM: 1.11.00 WWE Radio: 1.04.0 ExtROM 1.11.171 WWE
HTC Kaiser 1: ROM: Polymod 2.1D Final-Dark : Radio: 184.108.40.206
HTC G1 Dream: GammaFly V1.3 RC2, AmonRa, DangerSPL, Radio 2.22.27.08
Polymod 2.1D Final Version: It's Alive!
Android boot splashes and boot animations
(for Kaiser )