if you are a porgrammer
you will understand this
First i am starting with bufferoverun in the driver stack space in any operation system
The windows TCP/IP drivers run in the kernel mode and have a limited stack space apart from the fact that only a little space is given the TCB(transmission control block) for entries

When there are too many request the kernel stack space buffer overloads and caues some slowdown in the total system and if this continos then it may crash but the prob here is that
if you write a program that sens numerous ICMP or some other packets throught UDP or TCP
the firewall or the IDS analyses the logs instantly and block you access think of it

Denail of service is also a part of buffer overrun

/Revanth