virtualbox.org

When I am About to start any virtual machine, That machine window shrinks to a minimum, and, Although maximize returns alone to shrink in size.

And Also it is a little slow, somewhat lagged. I've tried uninstalling and reinstalling without positive changes.

What I can do?

We will need to see a VM log file.

Right click the VM in the GUI. Select "Show Log". Save "VBox.log" to a file. Compress that file and attach it to a message here. Make sure the VM is fully shut down before taking a log.