I experience a strange problem with RH6.2/RH6.1 startup when startup script tries to set clock (I tracked it down to command "hwclock -- hctosys -u") my system stops responding (I tried on two different AMD Athlon Motherboards: ASUS K7V and ASUS K7M). Only way to continue on ASUS K7V (with RH6.2) is to press [Print Scrn/SysRq] key, but on ASUS K7M (with RH6.1) only reset switch. Strange is that this problem happens on K7V (almost) every boot and K7M at least at every third boot. With K7M problem comes up almost certainly when IDE HD drives are changed or swapped, on K7V it seemed to coincident with IDE CDROM presence but now it happens every time with or without CDROM. Same result with "hwclock --hctosys -u" on console, too. (At the same time third machine with K7M board (with RH6.2) does not have this error.)
Sorry, but it sounds like that's a hardware problem; these machines apparently don't implement the RTC clock interface too well...