Problem importing a Win7 machine onto ESX4 host

Hi Folks,

Having an issue while importing a Win 7 machine with min disk size (28 GB) on a ESX4 host with vCenter converter 5.0.0.

vCenter version is 4.0.

Error message is-

"Import Machine

Failed to take snapshot of a source

volume. Possible causes include not

having any NTFS volumes on

Windows XP or Windows 2003

source systems, and not having

enough free disk space."

.

There is enough free disk space on the datastore where I am trying to import.

Can anyone let me know possible cause and solution to this?

Thanks

vmrockin