Blue screen crashing after installing NIS 2011 upgrade

I upgraded to NIS 2011 a few weeks ago and my computer continually crashes, blue screen points to problem file SYMEFA.SYS.

 

When I searched for this file it found this:  C:Windows\systems32\drivers\NIS 1201000.025

 

I downloaded the upgrade link without removing the previous NIS 2009, which was not mentioned, I assumed it would do it automatically.

Could this be the reason I am experiences the crashes??

 

Please let me know what I need to do to fix this problem, thanks.