installing an application nothing happen

I have a win2000 server and everytime I try to install a new application nothing happens (insatllation does not start). Currently the only applications installed in it are office2000, pervasive 2000, nav corporate edition and a custom application for estimating with pervasive its database.

My server has 512ram, 10gb free space,p3 900 and using adaptec 2100 for raid.

Hopefully someone can help me.