Norton Antivirus 2008 Internet Expl 8 add on error

Hi there I have recently installed Internet explorer 8. I kept getting an application error message pop up each time I opened an intenet screen or close it down with numbers and a message saying memory could not be read.

 

It appears that if i disable the symantec intrusion prevention add on in internet options, the message disappears and internet explorer functions as normal

 

However I am a little concerned that I have now turned off intrusion prevention add on and frightened my computer is at risk!!??

 

Please can anyone help!

 

Many thanks