Does defragmenting in Windows.....

kill your datas? or crush your PC? I do defragment sometimes but I'm so scared each time I do it. So please tell me the answer. Because my external hard drive is being quite slower then usual nowadays, I think I have to defragment the ex hard drive. Or is there anyother solution??

Anything that accesses the hard drive can potentially cause corruption through data corruption or a mechanical malfunction within the drive, which is why you should always back up your data. That said, defragmentation is particularly drive-intensive, so there's a higher chance of a problem occuring than with simple read-writes, because you're doing a lot more drive accesses.

Defragmentation shouldn't change anything if it works correctly. There's always the possibility of bugs in the program, drive problems, or memory corruption, so, again, frequent back-ups are the only sure way to keep your data safe.

If your external hard drive contains a FAT file system, or some other type of older file system, it could very well be fragmented. If it's NTFS (Windows XP's default file system), ext3, ReiserFS, or another modern, journaled file system, it shouldn't be fragmented. The Windows defragmenter program should tell you whether or not the drive is fragmented. If it's not, the drive could be getting ready to go kaput.