I'm not able to switch to Seamless Mode in VirtualBox with Ubuntu 10.04 or 9.10 as guest OS's. I have tried the seamless mode with XP as guest OS, and it works absolutely fine. The host OS is Windows 7. I have in-built Via/S3G Unichrome Pro IGP graphics, and I have allocated 30 MB out of 64 MB of graphics memory. I've also 1.5 GB of RAM. I also tried installing Guest Additions but it still didn't work. VirtualBox version is 4.0.4r70112. How can I get the seamless mode to work? Please help!