Hi Benny.
Don't know if I've got this problem on my 40D, I haven't connected with USB for years! Have you tried the Canon EOS utility, this is at least made by Canon to connect their cameras to a pc. What OS are you using, try restarting your pc while the camera sits without batteries, try connecting then power on camera and power on then connect camera.
I have just looked and can't find it in the menu, but it's late here and I may have missed it, I've had problems on one of my cameras not connecting because of a menu setting of ptp or normal output, may have been 20D.
Not a problem until you want remote shooting over USB! Hope you get to he bottom of this.
Edit
Welcome to the forum Benny.
End edit.
Cheers Graham.
Hey All, new member 
I've had my 40D for a while now and I've got a problem.
It's not been a problem and still isn't, but if I plug it in via USB to my PC or Tablet, all I get is Busy on the lcd, then nothing..
It won't connect to the PC as a mass storage device, It won't even connect using EOSInfo to check the Shutter Count..
I took it to my local specialist shop and same thin, I can't connect my 40D to a PC using USB.. I've tried FW 1.0.8 and 1.1.1.
Anyone else have this issue..?
Thanks
