Seamless mode and .Net framework

[essedi]

After that I've installed the Microsoft .net Framework (ver. 3.5) the seamless mode doesn't work anymore. It maximize the window to full size but the WinXP desktop doesn't disappear.
If I use the snapshot that I took Just before the installation it works fine.
Is there something I can do for this ? (as well as by removing .Net that I unfortunately really need).
Thanks

[essedi]

Fixed with upgrade to 4.0