While and If messing up my program?

[CJ]

   Hey, I'm new to the Python world, but I do have experience in several 
other languages. I've been running through a tutorial, and I decided that 
I'd make a program that runs through a list, finds if there are any 
duplicates. The program, doesn't work, but since its a first build I 
wasn't too worried about it. I'd be highly impressed if I got the program 
to run correctly in the first build, I want to debug it myself later.

   What does worry me, is that I can't seem to get the program by a 
certain spot. It keeps giving me the same error, and I don't know why.

The code:

ttllst=[4,3,45,3]
cnto=0
cntt=1
rept=-1

print cnto
print cntt
print ttllst[cnto]
print ttllst[cntt]
choice=raw_input("Begin? ")
if choice == "yes" or choice == "y":
    while cnto<>len(ttllst)+1:
        if ttllst[cnto]==ttllst[cntt]:
            rept=rept+1
        if cntt==len(ttllst):
            print ttllst[cnto],"appears in the list",rept,"times."
            cntt=-1
            cnto=cnto+1
            rept=-1
        cntt=cntt+1
    print "done."



After running the program I get error:

Traceback (most recent call last):
  File "C:\Python24\Projects\repeatfinderlist", line 13, in -toplevel-
    if ttllst[cnto]==ttllst[cntt]:
IndexError: list index out of range


Now, if I remove the while, and the If/choice lines like so:


ttllst=[4,3,45,3]
cnto=0
cntt=1
rept=-1

print cnto
print cntt
print ttllst[cnto]
print ttllst[cntt]
if ttllst[cnto]==ttllst[cntt]:
    rept=rept+1
if cntt==len(ttllst):
    print ttllst[cnto],"appears in the list",rept,"times."
    cntt=-1
    cnto=cnto+1
    rept=-1
cntt=cntt+1
print "done."


I get no errors. The program doesn't work, granted, but I get no errors. 
Can anyone tell me what I'm missing?

Thanks!
-CJ