Applications iPhone 3G

I have synched my Iphone with my PC.
I removed an apps I needed to remove and then reinstall.
I removed it. I then went to the Itunes store got it back for free.
Now when I go to the Applications page in Itunes I cant select anything. I cant even use the slider to move up and down. Everything is sort of greyed out. I can go to any of the other tabs and select or deselect and everything works fine but not the Application page.
I want to get the apps I reinstalled back onto my Iphone.
What have I done or what do I need now do?
TIA
Xerxers
Ipaq Windows XP