The operation can't be completed because the item XXXXX is in use

I get an intermittent issue when attempting to delete certain folders when connecting via my mac (snow leopard 10.6.4) although this does not always effect all folders when attempting to delete, it seems happen on a regular basis.

I have checked all open application etc to see if the the file is locked by the OS, but this doesnt seem to be case. I have full admin rights to every share also.

Is there anyway to force delete in snow leopard, or anyway of determining why/what process is causing the file to lock? or this a known issue with the product. I have a large number of folders I can’t delete at the moment because of this issue.