Hi John, it sounds like this relates to your particular device driver for the controller. May I ask, what controller are you referring to? When you installed windows 7 it sounds like there was an incompatibility issue i.e. your controller was not compatible with windows 7. So it sounds like you need to download the latest device drivers from the Median website. I have provided the link below for you but you will need the serial number on your computer before you can progress further. There should be a label on your pc somewhere giving this information. If you provide this to me, I can carry out further research on your behalf.
Once you have input the serial number you can locate your exact pc model number and hopefully find available device drivers. I would download and save to your desktop so that it's easily accessible. Then, in Device Manager, this is where all your devices and controllers are listed you should see a yellow question mark or a red x, this indicates that there's a problem with a particular device or controller, I'm assuming you will see this for the controller you are referring to. To access device manager type in following in the "start search" text box: devmgmt.msc
Once in device manager you can locate particular controller and click on the plus symbol to expand list futher then right click on controller and select properties. Then you click on the Driver tab at the top of this window and then click on Update Driver. You can then locate the particular device driver that you need from the device drivers you downloaded and placed on the desktop. I'm hoping this should sort out your problem. The first and most important thing to do though is to access the Medion site and try and locate the device drivers for your particular pc.
If all goes well and you are up and running then there is something I strongly recommend you do and that is use a free tool called Double Driver. This free tool recognises all the device drivers you have on your system and backs them up so if you have a problem like this next time you will already have your device drivers backed up and can then access them immediately and restore them. Carry out the back up to an external hard drive or something. Here's the link for this tool and once on the page, you can down load where it says download Double Driver.
Well, good luck and I hope that this information is helpful to you. Let me know if I can be of any further assistance. Andrew