WD My Passport SES recognized but not functioning

Hello,

I've been having problems with my external hard drive. Yesterday I plugged it into a DVD player and a laptop, and it worked fine. Today I tried connecting it to my own computer, where it generally works flawlessly, and couldn't make it work.

My computer recognized the hard drive but no letter is assigned to it and I cannot access the data; it's as if it wasn't installed. Also whenever connected my computer works very slow, occassioally freezing. It appears on my list of computer devices when connected but whenever I try to do something from there it freezes.

What options do I have left? is it possible my external hard drive was infected in the other laptop, and if so, is there anything I can do about it without losing any data?

Thanks!