System Constantly Crashing

My system the past several weeks has been constantly crashing, mostly at startup. It goes to the blue screen and gives a STOP error. I have not written down the error each time but I know that one time it was the nv4_disp.dll, which is an NVIDIA driver. Another time the error it gave was ndis.sys, which I do not know what that is. I was wondering what this means exactly and what I need to do to fix it.

A separate question I have is that I hook up an external monitor to my laptop through my DVI port, and I am connect and disconnect the DVI cable while the laptop is on. Is this a bad practice?

Did you updated the NVIDIA drivers lately and then started to experience the crashes. I did an update on one a few weeks ago and it started crashing right off so I rolled the NVIDIA driver back and it stoped crashing when i rebooted.

no i didn't update the drivers but I was trying to update the drivers after the crash so i uninstalled the drivers but then they just reinstalled themselves on startup. this seemed to help things out for a while until i recently got this ndis.sys error message