One minidump is not enough to really pinpoint a problem. Your single minidump points to NDIS.sys:
"The NDIS library (Network Driver Interface Specification) is contained in
ndis.sys. It is a collection of routines that applications can invoke to
perform network-related operations"...
As I said, this alone doesn't guarantee enough information for a true diagnosis. This could relate to a bad modem driver, network card driver or a memory problem