The drive could be developing a fault or it could be the PCB in the enclosure that's faulty (a common problem with all external hard drives). You can test the drive with SeaTools for Windows to see if it comes up with anything that indicates a faulty drive: http://www.seagate.com/support/downloads/seatools/
(In case you are wondering, SeaTools can be used to test any make of hard drive, not just Seagate ones)
Is it one of the removable cartridge models or a standard external hdd that connects via USB?
Has it ever worked properly on that computer? Does it work on any other computer? Can you do anything on the drive from the computer without a problem?
What OS is your computer and did you load any particular drivers for it?
it is a standard ehdd that connects via usb. it used to work well with my computer and other's. fyi, i use Windows 7 ultimate with intel dual core t2330. after ive format it, i can have access to the ehdd but whenever i want to transfer any file into it,it just freeze. i think it might be something wrong with it. just couldnt figure it out yet
That indicates bad sectors that have not yet been mapped out for nonuse, and they are an issue if they keep happening the drive is bad. You might just see some intermittently, and then they will be remapped and the reallocated sector count will rise and that sector will not be used again. If the reallocated count keeps rising that also indicates a bad drive.
To clean up the drive and find out if it stops having bad sectors you can download DBAN ( http://www.dban.org/ ) and then reformat and quick erase in DBAN, which can do a zero write. Then all bad sectors should be gone. Any new ones that pop up fast indicate a bad drive.