external hard drive

I have a toshiba external hard drive formatted as Mac OS X Extended (journaled). When it is mounted on my macbook, it takes a long time to load and I get the beach ball for about 10 minutes before anything loads. Even when everything loads up, some files open and some won't. The files that won't open gives me the "corrupted data" error. When I try to copy from the external to my macbook, I get the -36 error (files can not be read or written). When I copy certain files from my macbook to the external I also get the same error.

I absolutely cannot lose the files on my external, can someone please help me?

Any help is appreciated!

P.S. the drive was originally formated as FAT. I had the files on there for some time but then I copied the files over to my macbook, formatted the drive as Mac OS X Extended (journaled) and copied the files back onto it. I did try that "dot_clean" in terminal but it didn't do anything. I also tried to repair it but no luck either.