Problem with export VM to OVF ( not enough resources)

Hello,

I'm trying to export a few VMs to OVF. Successfully I've exported 3 machines but another export finished with error "Failed to export Virtual Machine:Insufficient system resources exists to complete the requested services". I've checked destination drive for free space and there is enough space.

Any ideas ?

(Esx4.1, vCenter 4.1)

Regards,

Pawel