I recently received an error from my Time Machine backup saying that I needed to reformat and erase my external hard drive before Time Machine could back up to the hard drive. I followed the instruction and wiped my backup clean and reformatted. I then set up Time Machine backup again using the same hard drive but was curious about the estimated completion time. I have about 500 gb of data to backup and am using USB 2.0. Time Machine is estimating that it is going to take "about 10 days" to backup!! That can't be right can it?? It has been backing up with a few hours now and I am only at 7 gb currently. Is there something wrong with my hard drive or does this sound about right??