problem with tone and softwareserial for GPS

I'm having a problem using tone and the softwareserial library (which I'm using to connect to a GPS). It took me a while to figure out the problem. The sound generated by tone was being corrupted (cutting in and out). I figured this out when I disabled softwareserial in my program, like this sws.end(); I'm assuming the GPS was sending data at the same time the tone was trying to be played.

Is there an alternative software serial library that doesn't effect tone?

Or, does the current softwareserial library work with tone only on certain pins? I'm currently using pins 8 & 7 for softwareserial and pin 5 for tone.

As a followup, it looks like the problem was with the SoftwareSerial library. I changed over to the AltSoftSerial library (AltSoftSerial Library, for an extra serial port) and the problem with the tone no longer happens.