1)LCD reset routine is much important that cable length ,
on longer cable You must slow down operations (add NOP's).
Play around with reset routine.
2)Abnormal fast execution - first check XTAL, second check
reset circuit and supply, but error will be in code - with 99% probability.

Below is piece of code, i'm using to reset LCD 16x2 - You see
reset is performed 3..4 times, this can be asumed as error or
irrational, but tis code is working on more than xx,000 pcs
taximeters.

regards,
Stefan


LCDRESET:
mov r2,#25
call delayr2 ;250ms
call xxxreset
mov r2,#25
call delayr2
call xxxreset
mov r2,#25
call delayr2
call xxxreset
xxxreset:
LCALL SETLCD8
LCALL SETLCD8
LCALL SETLCD8
MOV A,#8 ;DISPLAY , DISPLAY OFF,CURSOR OFF,BLINKING OFF
LCALL WLCDCOMMAND;
MOV A,#13 ;DISPLAY , DISPLAY ON,CURSOR OFF,BLINKING OFF
LCALL WLCDCOMMAND ;
mov r2,#3
lcall delayR2
MOV A,#9 ;DISPLAY , DISPLAY OFF,CURSOR OFF,BLINKING ON
LCALL WLCDCOMMAND;
MOV A,#12 ;DISPLAY , DISPLAY ON,CURSOR OFF,BLINKING OFF
LCALL WLCDCOMMAND;
MOV r2,#3
lcall delayR2
LCALL CLEARLCD
LCALL CLEARLCD
LCALL CURSORLCDHOME
MOV A,#6 ;ENTRY SET ;CURSOR INCREASE ; DISPLAY IS NOT SHIFTED
LCALL WLCDCOMMAND ;
MOV A,#16;20 ;SHIFT ;CURSOR SHIFT ,LEFT
LJMP WLCDCOMMAND;
SETLCD8:
mov r4,#4
MOV A,#BUS8SET_LCDCOM
setlcd8loop1:
lcall LCDCOMMAND ;send withowt busy checking
mov r2,#2
lcall delayr2
djnz r4, setlcd8loop1
SJMP WLCDCOMMAND ;wait ready and send


CLEARLCD:
MOV A,#CLRDISPL_LCDCOM
SJMP WLCDCOMMAND
CURSORLCDHOME:
MOV A,#CURSORHOME_LCDCOM
SJMP WLCDCOMMAND


WLCDCOMMAND:
LCALL LCDCOMMAND ;write command
SJMP WAITLCD ;wait ready



BUS8SET_LCDCOM EQU 56 ;