Ok, tried swapping it over to another pin, no help. So, it's definitely in the code. So, as requested, here are relevant excerpts from said code:
Just for reference, pin list:
8 P3.4 IN Q8
7 P3.3 OUT C
6 P3.2 OUT P/S

First, my interrupt init variables:

IEX EQU 088H
IPX EQU 000H
TCONX EQU 005H
TMODX EQU 010H

Now, my variables:

DPORT EQU 090H ;
CBIT EQU 3 ;
PSBIT EQU 2 ;
QBIT EQU 4 ;
SWPORT EQU 021H
DIP1: reg SWPORT.0
DIP2: reg SWPORT.1
DIP3: reg SWPORT.2
DIP4: reg SWPORT.3
DIP5: reg SWPORT.4
TBLOCK: reg SWPORT.5
EBPASS: reg SWPORT.6
SMLOCK: reg SWPORT.7

Next up, CPU init:

CLR A
MOV B,A
mov DPTR,#0
MOV P1,#0FFH
MOV P3,#0FFH
MOV PSW,#PSWX
MOV PCON,#PCONX
MOV IE,#IEX
MOV IP,#IPX
MOV TCON,#TCONX
MOV TMOD,#TMODX
MOV TH1,#T1MSB
MOV TL1,#T1LSB
MOV TH0,#T0MSB
MOV TL0,#T0LSB
SETB TCON.6
MOV IE,#IEX

Now, the actual code:

MOV A,#00H
clr TCON.6
clr DPORT.PSBIT
setb DPORT.PSBIT
SERIALA:
clr c
clr DPORT.CBIT
setb DPORT.CBIT
MOV C,DPORT.QBIT
RRC A
DJNZ R0,SERIALA
MOV SWPORT,A
setb TCON.6

Ok, that's it. Such a small portion of code to be working on for the month or so that I've been playing with it :)
Oh, well, Thanks for helping me out, I really appreciate it.
Oh, one more note: At first, I thought my problem might be with the SWPORT variable, since it's broken down to regs, but it all works right... If I bypass the DIP portion of code and manually set it to a value (mov swport,xxH), the rest of the program responds to that code normally.