Hard drive problem [Slow internal copy vs fast external copy]

Here's the problem: When I try copying 187MB from the C drive (working fine) to the internal D hard drive it took 20 minutes. Did the same to my outboard HD, took about 3.5 minutes. Then tried the same from D back to C and it took seconds. Going C to D, effected the whole computer system, making it hang, which didn't happen when writing to the outside drive. The hanging thing is another symptom. It seems to get ready to copy, and hangs. Once the copy begins it's better but the computer runs very slow. This wasn't like this a month ago. I'm not sure if this points to a system problem or a drive problem. Drive is a few months old.
Any other tests possible. Or suggestions.

 

I expect the internal drives are IDE, not SATA.

Check the data cables. Even until recently, motherboards/computer systems have been supplied with one 80 lead cable and one 40 lead cable. It is expected that two hard disk drives are run on the primary IDE controller (80 lead) and optical drives are run on the secondary controller (40 lead).

Check the jumper setting on the second HDD. There should be a manual/user guide available for download at the the drive manufacturer's website.

Matt