I'm using a 16f877 with max 232 at 4mhz

I'm having problems reading multiple variables in 1 Hserin string
It works, but after some times it hangs so I think there is a buffer overflow
What worries me is that when i measure with an osciloscope, there are pulses on portc.7 the UART RX even with no max232 chip connected ???

Here is a part of the code:

DEFINE HSER_RCSTA 90h ' enable serial port,
' enable continuous receive
'
define HSER_TXSTA 24h ' enable transmit,
' BRGH=1
'
define HSER_SPBRG 103 ' set baudrate to 2400
DEFINE HSER_CLOERR 1 ' automatic clear overrun error

TRISB = %00000000
'OPTION_REG.7 = 0 ' Enable PORTB pullups
TRISC = %10000000
TRISD = %00001111
TRISE = %000

loop:
Hserin 500,LCD,[wait ("TAR"),dec3 var1,wait ("ANT"),DEC3 var2,wait ("AUX"),DEC3 var3,wait ("EXT"),DEC3 var4]


LCD:
pause 10
Lcdout $fe, 1 ' Clear screen

Lcdout "VAR1: ",#VAR1," VAR2: ",#var2

Lcdout $fe, $c0, "VAR3: ",#VAR3," VAR4:",#VAR4

Goto loop

Any Idea ?