Asks for a disk to be inserted in drive D

I have just installed eM Client on a new machine running Windows 7.I have created an email account. Sometimes when I load eM Client it works. Most of the time I get an error message that says “There is no disk in the drive. Please insert a disk into drive D.” Does anyone know what the problem might be?

Hello,

can I ask you if there is no other program in the background that could cause this? Like another installation or some media player etc.

regards
Jan