Why can't I copy data from my computer running ubuntu 11.10 to an external drive? Does it have anything to do with the format of the drives or something along those lines? What do I need to do to be able to transfer data freely between my computer & other external drives?
If it is a NTFS drive(common windows partition) you can install support
This should help you to transfer data to your external drive
Otherwise, to go between windows mac and Linux is FAT32, Make sure there is no data on the drive before formating the drive, there are other limitations with this format such as speed and single files over 4GB.
And if it is a Western Digital drive there are other problems, aka a lot of posts like this "Can't Mount Western Digital My passport external Hard drive". the WD drives come with "smart ware" which has password software and stuff, to use it on linux you need to run the software on windows(or mac if your using) to disable this stuff and use it as a normal drive how-to-reomove-wd-smartware-virtual-drive
once it opens as a regular drive in windows(without wd software) you should be able to get it going with the ntfs drivers (paste the code in the terminal).
If this doesn't help please post specifics about what drive it is or what it is doing.