Powering on my esata external disk makes windows freeze for 15-30 seconds

Powering on my esata external disk makes windows freeze for 15-30 seconds

I have a SATA disk in an external eSATA enclosure. Most of the time it's powered off, but when I turn it on windows hangs for 15-30 seconds. No sound, no mouse, nothing. Then after 15-30 seconds, everything is fine again.