AVR-Chat

I am designing a robot and used an ISP based on the Sample Electronics
programmer cable.  This ties printer port pins through 360 ohm resistors
to the programming port pins on the AVR.  The chip that I am using is the
Tiny2313.  I also have a FAN8200 H-Bridge chip with the direction inputs
tied to PB6 & PB7 (MISO & SCK respectively) as well as an on-board speaker
tied from PB5 (MOSI) directly through the speaker to +V.

I noticed that when I tried to program the chip, the downloader software
(built-in to BASCOM AVR could not determine what type of AVR chip I was
programming.  When I removed the speaker and the FAN8200, it programmed
the 2313 without any troubles.  After playing around with the prototype, I
found that an LED appears to cause no trouble to the programming, and that
if I run the speaker through a 360 ohm resister to +V, it seems to work.

My questions are these:

1)  Are there any restrictions on use of the ISP pins for other than
during programming?  In other words, what other things may/will cause the
programmer to not find the AVR chip?

2) Also, is this related specifically to the Sample Electronics
programmer, or will I find the same limitations with one of the buffered
ISP cables (6- or 10-pin)?

Thanks in advance,

Art