slow copying/cloning of vm images

hello everyone

I'm setting up a new virtual environment on a brand new DL380 server for testing purposes.

at first I tried hyper-v solution.... BIG MISTAKE... so i ended up reimaging the server and installing ESXi 4,  64bits

everything was going fine until i had to copy a 6GB vmdk file from one folder to another in the same datastore... time remaining : over 1000 minutes!!!

I then requested access to the vCenter in order to use the out-of-the-box option to clone vm's. Same behavior !!

Any ideas would be greatly appreciated!!!!

I have a 1TB datastore

48GB of RAM

Thanks.