I got tired of this anti-virus issue so I decided to rebuild the astra.cab myself, here's how;
1) Grab the latest version of Astra from
http://www.sysinfolab.com/
2) Extract contents to a folder eg. C:\dosapps\astra
3) Find a copy of MS's cabarc.exe, it might be in a resource kit not sure
EDIT: Get it here:
http://support.microsoft.com/kb/310618
4) Place cabarc.exe in c:\dosapps
5) Create a blank text file in c:\dosapps and rename to makecab.bat
6) Edit file and paste this line @cabarc -m LZX:21 -p -r -P astra\ n astra.cab astra\*.* save file and double click it
You should now have a new astra.cab in c:\dosapps, move it to your dosapps folder within UBCD and recreate your ISO
This was tested with ASTRA 5.45, there are no AV issues with it.