reboot using modem

I have had a random reboot problem when I try to log on to my isp with either wvdial or kppp. After this happened several times in a row this morning I was finally able to see something in the /var/log/messages. The last line in most cases was linux kernel:PCTel initialization.Country code 1. In a few cases the last line was ALSA../alsa-kernel/core/pcm_lib.c:121:unexpected hw_pointer value (streams=0,delta:-5072,maxjitter=5120): wrong interrupt acknowledge? Does anyone have any idea as to what is going on, this is becoming a big pain. David