Your Inspiron 1200 is five or six years old? Probably time to replace that 30GB hard disk drive.
That Celeron M 350 1.3Ghz CPU was weak and sluggish back in 2005. And the Intel Extreme Graphics 2 IGP graphics chip isn't helping much. All-in-all not well suited for watching HD movies over NetFlix. Choose the lower quality streaming options from NetFlix.
Surprisingly I just had just had a similar experience on my old Dell Latitude D800 laptop. It was quickly evident that the old laptop couldn't keep up with the the NetFlix video. I exited NetFlix and afterwards went through normal shutdown procedure. Next day when I turned on laptop, it would not boot from hard drive. I swapped with a backup hd and it would not boot either. Ouch. Hard to believe that viewing a netflix video could cause this problem.
The last time my laptop worked was when I was trying to watch movies online through Netflix. Now my hard drive is shot and I don't know what the heck?