1. Your instrument is not "very old". I would kill for a 6890. I have a Varian GC I run daily that was installed 20 years ago.
2. The floating point exception issue is one I've seen with Agilent's LC Chemstation. Here's the thread I posted that related to my problem. However, you should contact Agilent and ask them if there might be a software patch or another recommended course of action before you start doing anything extreme.
viewtopic.php?f=4&t=13526&hilit=chemstation
I believe all I did was perform the windows cleanup and defragment my drive on that computer, but I believe (perhaps remembering incorrectly) that there are some caveats from Agilent about particular drive maintenance activities that you should follow...
And a little Googling found the article I remember seeing before on computer maintenance.
http://www.chem.agilent.com/Library/Sup ... _maint.pdf