So I got tired of the slowness of my external disk and decided to shove it inside my laptop (which had a spare HDD slot... it's quite a big laptop...) Everything works fine (except that I had to cram a 12.5mm disk into a normal 9.5mm space... it fits though, haha). However it's a bit odd - getting the properties up for the disk, the "readyboost" section is still there. And there's no recycle bin. These two things tell me Windows (7) still thinks the disk is an external device, even though it's not. There must be a little flag somewhere, can I change it? Or should I have reformatted. This is not really a viable option as it's a 1TB disk and I don't have enough space elsewhere to transfer it all... Thanks if anyone has any bright ideas!
What file system is it formatted in? Also, is it set up as a basic disk or a dynamic disk? Have a look in computer management (disk snap-in) and that might shed some light.
Is it a true SATA header in the other drive bay? If it's an internal USB-SATA or something strange like that, you might be encountering these problems. Are there any settings for the second drive bay in the BIOS?