tcp/ip stack

last Fri my pc was operating perfect..shut down..turned on Saturday and could
not connect with internet..did all the basics to try to remedy, nothing
worked.. Called Comcast..after a few calls plus transfering up tech chain was
given tkt # and tech was at my door in 4 hrs..first time ever..plus comcast
never does anything in a hurry!! The tech came prepared to replace, and did
replace, my modem altho old one pinged. He did many mysterious things plus
put a disc into my processor which seemed to be some sort of analysis
thing..he sort muscled the pc around i.e. overriding a lot of audio and video
complaints..He got me up and running in less than an hour..His diagnosis was
"tcp/ip stack blown". Could someone tell me if this situation comes about
because of my ignorance..or did Comcast fiddle in the night with their stuff
and cause this..I don't have a clue..He said "it just happens"...and..could I
get my hands on a analyizer/debugger so could fix myself??
f more info is needed just ask as I don't even know what's pertinent.