Recover files from Maxtor Mini lll

When I plugged my hard drive the computer slows down and it takes a long time to read it. When I try to go in the drive it gives this error message "The system cannot find the device specified". I check the Device Manager and Disk Management and the drive show up fine. I also change the letter path. What other options do I have to open my hardrive and recover my files. I'll appreciate your help.