Usb port ceases to work when any device connected to second port

Well, I'm assuming your speaking of a pair of ports either on the front or the back of your system. Most USB ports are paired (i.e. the ports on the front of your system are cabled into a single connector of your motherboard). What if you put the PenDrive in the front and the printer in the back? Another interesting alternative is that if you have any empty USB ports on the motherbard, use something like one of these to seperate and test your theory: http://goo.gl/K2VPu5 or http://goo.gl/VzRZMo. These are great for DIY server, NAS, or AIO where you boot off of a USB drive that otherwise would be hanging outside of the box. In your case though, this will be a test for your PenDrive in one while your printer is in another.

Of course, I cant help but wonder what we're missing here. Do you have a bad printer/USB connection or PenDrive? Is the printer drawing too much current?

Good luck!

Your USB ports on your computer are plug and play. If you have issues with your USB port, it is port related, driver related or device related. The following solutions will help you identify the problem to resolve your USB port issues.
To Identify a Working USB Port
Begin troubleshooting your USB ports by checking Device Manager to see if your USB ports or hubs are working properly.

1. Click the Start button. ClickControl Panel.
2. ClickSystem and Maintenance.
3. ClickDevice Manager.
4. Double-clickUniversal Serial Bus controllersand check to see if all your USB ports, hubs and controllers are functioning correctly. Any devices not functioning will have a yellow exclamation mark in front of them.
5. If Device Manager shows any USB ports, hubs or controllers are not functioning, check for updated drivers.

To Update the USB Port Driver

• Information onHow to Download and Install a Driver

• Watch a Video on Steps to Update Bios on Your Computer.
1. When the update process is complete, your computer will restart again to load the operating system with the new driver version installed.

All the usb ports works fine when one device printer or pendrive is connected. Suppose if I connect to usb 1 pendrive it works. If I connect printer to usb 2 it will not work. If I remove pendrive printer starts working in usb 2. Same thing happens in usb 3 & usb 4.

As you stated the device works in one slot but not the other , tells you there is problem with that usb port , don't use those ports , best thing to do is purchase a PCI USB card if you need more USB ports .