>After loading service pack 4 we are not in a position to load any anti virus software. Please help us.
>
>Win NT ver - 4.0
>Memory -128MB

Bijaya,

You have loaded sp4, but for what? If its NT, it should be sp6a, VFP should be Visual Studio sp5. However, unless your AV software has specific sp requirements, I doubt whether installation of a sp is the problem.